//! Generic OpenAI-compatible provider.
//! Most LLM APIs follow the same `/v1/chat/completions` format.
//! This module provides a single implementation that works for all of them.

use crate::providers::traits::{
    ChatMessage, ChatRequest as ProviderChatRequest, ChatResponse as ProviderChatResponse,
    Provider, StreamChunk, StreamError, StreamOptions, StreamResult, ToolCall as ProviderToolCall,
};
use async_trait::async_trait;
use futures_util::{stream, StreamExt};
use reqwest::Client;
use serde::{Deserialize, Serialize};

/// A provider that speaks the OpenAI-compatible chat completions API.
/// Used by: Venice, Vercel AI Gateway, Cloudflare AI Gateway, Moonshot,
/// Synthetic, `OpenCode` Zen, `Z.AI`, `GLM`, `MiniMax`, Bedrock, Qianfan, Groq, Mistral, `xAI`, etc.
pub struct OpenAiCompatibleProvider {
    pub(crate) name: String,
    pub(crate) base_url: String,
    pub(crate) api_key: Option<String>,
    pub(crate) auth_header: AuthStyle,
    /// When false, do not fall back to /v1/responses on chat completions 404.
    /// GLM/Zhipu does not support the responses API.
    supports_responses_fallback: bool,
    client: Client,
}

/// How the provider expects the API key to be sent.
#[derive(Debug, Clone)]
pub enum AuthStyle {
    /// `Authorization: Bearer <key>`
    Bearer,
    /// `x-api-key: <key>` (used by some Chinese providers)
    XApiKey,
    /// Custom header name
    Custom(String),
}

impl OpenAiCompatibleProvider {
    pub fn new(name: &str, base_url: &str, api_key: Option<&str>, auth_style: AuthStyle) -> Self {
        Self {
            name: name.to_string(),
            base_url: base_url.trim_end_matches('/').to_string(),
            api_key: api_key.map(ToString::to_string),
            auth_header: auth_style,
            supports_responses_fallback: true,
            client: Client::builder()
                .timeout(std::time::Duration::from_secs(120))
                .connect_timeout(std::time::Duration::from_secs(10))
                .build()
                .unwrap_or_else(|_| Client::new()),
        }
    }

    /// Same as `new` but skips the /v1/responses fallback on 404.
    /// Use for providers (e.g. GLM) that only support chat completions.
    pub fn new_no_responses_fallback(
        name: &str,
        base_url: &str,
        api_key: Option<&str>,
        auth_style: AuthStyle,
    ) -> Self {
        Self {
            name: name.to_string(),
            base_url: base_url.trim_end_matches('/').to_string(),
            api_key: api_key.map(ToString::to_string),
            auth_header: auth_style,
            supports_responses_fallback: false,
            client: Client::builder()
                .timeout(std::time::Duration::from_secs(120))
                .connect_timeout(std::time::Duration::from_secs(10))
                .build()
                .unwrap_or_else(|_| Client::new()),
        }
    }

    /// Build the full URL for chat completions, detecting if base_url already includes the path.
    /// This allows custom providers with non-standard endpoints (e.g., VolcEngine ARK uses
    /// `/api/coding/v3/chat/completions` instead of `/v1/chat/completions`).
    fn chat_completions_url(&self) -> String {
        let has_full_endpoint = reqwest::Url::parse(&self.base_url)
            .map(|url| {
                url.path()
                    .trim_end_matches('/')
                    .ends_with("/chat/completions")
            })
            .unwrap_or_else(|_| {
                self.base_url
                    .trim_end_matches('/')
                    .ends_with("/chat/completions")
            });

        if has_full_endpoint {
            self.base_url.clone()
        } else {
            format!("{}/chat/completions", self.base_url)
        }
    }

    fn path_ends_with(&self, suffix: &str) -> bool {
        if let Ok(url) = reqwest::Url::parse(&self.base_url) {
            return url.path().trim_end_matches('/').ends_with(suffix);
        }

        self.base_url.trim_end_matches('/').ends_with(suffix)
    }

    fn has_explicit_api_path(&self) -> bool {
        let Ok(url) = reqwest::Url::parse(&self.base_url) else {
            return false;
        };

        let path = url.path().trim_end_matches('/');
        !path.is_empty() && path != "/"
    }

    /// Build the full URL for responses API, detecting if base_url already includes the path.
    fn responses_url(&self) -> String {
        if self.path_ends_with("/responses") {
            return self.base_url.clone();
        }

        let normalized_base = self.base_url.trim_end_matches('/');

        // If chat endpoint is explicitly configured, derive sibling responses endpoint.
        if let Some(prefix) = normalized_base.strip_suffix("/chat/completions") {
            return format!("{prefix}/responses");
        }

        // If an explicit API path already exists (e.g. /v1, /openai, /api/coding/v3),
        // append responses directly to avoid duplicate /v1 segments.
        if self.has_explicit_api_path() {
            format!("{normalized_base}/responses")
        } else {
            format!("{normalized_base}/v1/responses")
        }
    }
}

#[derive(Debug, Serialize)]
struct ChatRequest {
    model: String,
    messages: Vec<Message>,
    temperature: f64,
    #[serde(skip_serializing_if = "Option::is_none")]
    stream: Option<bool>,
}

#[derive(Debug, Serialize)]
struct Message {
    role: String,
    content: String,
}

#[derive(Debug, Deserialize)]
struct ApiChatResponse {
    choices: Vec<Choice>,
}

#[derive(Debug, Deserialize)]
struct Choice {
    message: ResponseMessage,
}

#[derive(Debug, Deserialize, Serialize)]
struct ResponseMessage {
    #[serde(default)]
    content: Option<String>,
    #[serde(default)]
    tool_calls: Option<Vec<ToolCall>>,
}

#[derive(Debug, Deserialize, Serialize)]
struct ToolCall {
    #[serde(rename = "type")]
    kind: Option<String>,
    function: Option<Function>,
}

#[derive(Debug, Deserialize, Serialize)]
struct Function {
    name: Option<String>,
    arguments: Option<String>,
}

#[derive(Debug, Serialize)]
struct ResponsesRequest {
    model: String,
    input: Vec<ResponsesInput>,
    #[serde(skip_serializing_if = "Option::is_none")]
    instructions: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    stream: Option<bool>,
}

#[derive(Debug, Serialize)]
struct ResponsesInput {
    role: String,
    content: String,
}

#[derive(Debug, Deserialize)]
struct ResponsesResponse {
    #[serde(default)]
    output: Vec<ResponsesOutput>,
    #[serde(default)]
    output_text: Option<String>,
}

#[derive(Debug, Deserialize)]
struct ResponsesOutput {
    #[serde(default)]
    content: Vec<ResponsesContent>,
}

#[derive(Debug, Deserialize)]
struct ResponsesContent {
    #[serde(rename = "type")]
    kind: Option<String>,
    text: Option<String>,
}

// ═══════════════════════════════════════════════════════════════
// Streaming support (SSE parser)
// ═══════════════════════════════════════════════════════════════

/// Server-Sent Event stream chunk for OpenAI-compatible streaming.
#[derive(Debug, Deserialize)]
struct StreamChunkResponse {
    choices: Vec<StreamChoice>,
}

#[derive(Debug, Deserialize)]
struct StreamChoice {
    delta: StreamDelta,
    finish_reason: Option<String>,
}

#[derive(Debug, Deserialize)]
struct StreamDelta {
    #[serde(default)]
    content: Option<String>,
}

/// Parse SSE (Server-Sent Events) stream from OpenAI-compatible providers.
/// Handles the `data: {...}` format and `[DONE]` sentinel.
fn parse_sse_line(line: &str) -> StreamResult<Option<String>> {
    let line = line.trim();

    // Skip empty lines and comments
    if line.is_empty() || line.starts_with(':') {
        return Ok(None);
    }

    // SSE format: "data: {...}"
    if let Some(data) = line.strip_prefix("data:") {
        let data = data.trim();

        // Check for [DONE] sentinel
        if data == "[DONE]" {
            return Ok(None);
        }

        // Parse JSON delta
        let chunk: StreamChunkResponse = serde_json::from_str(data).map_err(StreamError::Json)?;

        // Extract content from delta
        if let Some(choice) = chunk.choices.first() {
            if let Some(content) = &choice.delta.content {
                return Ok(Some(content.clone()));
            }
        }
    }

    Ok(None)
}

/// Convert SSE byte stream to text chunks.
async fn sse_bytes_to_chunks(
    response: reqwest::Response,
    count_tokens: bool,
) -> stream::BoxStream<'static, StreamResult<StreamChunk>> {
    // Create a channel to send chunks
    let (tx, rx) = tokio::sync::mpsc::channel::<StreamResult<StreamChunk>>(100);

    tokio::spawn(async move {
        // Buffer for incomplete lines
        let mut buffer = String::new();

        // Get response body as bytes stream
        match response.error_for_status_ref() {
            Ok(_) => {}
            Err(e) => {
                let _ = tx.send(Err(StreamError::Http(e))).await;
                return;
            }
        }

        let mut bytes_stream = response.bytes_stream();

        while let Some(item) = bytes_stream.next().await {
            match item {
                Ok(bytes) => {
                    // Convert bytes to string and process line by line
                    let text = match String::from_utf8(bytes.to_vec()) {
                        Ok(t) => t,
                        Err(e) => {
                            let _ = tx
                                .send(Err(StreamError::InvalidSse(format!(
                                    "Invalid UTF-8: {}",
                                    e
                                ))))
                                .await;
                            break;
                        }
                    };

                    buffer.push_str(&text);

                    // Process complete lines
                    while let Some(pos) = buffer.find('\n') {
                        let line = buffer.drain(..=pos).collect::<String>();
                        buffer = buffer[pos + 1..].to_string();

                        match parse_sse_line(&line) {
                            Ok(Some(content)) => {
                                let mut chunk = StreamChunk::delta(content);
                                if count_tokens {
                                    chunk = chunk.with_token_estimate();
                                }
                                if tx.send(Ok(chunk)).await.is_err() {
                                    return; // Receiver dropped
                                }
                            }
                            Ok(None) => {
                                // Empty line or [DONE] sentinel - continue
                                continue;
                            }
                            Err(e) => {
                                let _ = tx.send(Err(e)).await;
                                return;
                            }
                        }
                    }
                }
                Err(e) => {
                    let _ = tx.send(Err(StreamError::Http(e))).await;
                    break;
                }
            }
        }

        // Send final chunk
        let _ = tx.send(Ok(StreamChunk::final_chunk())).await;
    });

    // Convert channel receiver to stream
    stream::unfold(rx, |mut rx| async {
        match rx.recv().await {
            Some(chunk) => Some((chunk, rx)),
            None => None,
        }
    })
    .boxed()
}

fn first_nonempty(text: Option<&str>) -> Option<String> {
    text.and_then(|value| {
        let trimmed = value.trim();
        if trimmed.is_empty() {
            None
        } else {
            Some(trimmed.to_string())
        }
    })
}

fn extract_responses_text(response: ResponsesResponse) -> Option<String> {
    if let Some(text) = first_nonempty(response.output_text.as_deref()) {
        return Some(text);
    }

    for item in &response.output {
        for content in &item.content {
            if content.kind.as_deref() == Some("output_text") {
                if let Some(text) = first_nonempty(content.text.as_deref()) {
                    return Some(text);
                }
            }
        }
    }

    for item in &response.output {
        for content in &item.content {
            if let Some(text) = first_nonempty(content.text.as_deref()) {
                return Some(text);
            }
        }
    }

    None
}

impl OpenAiCompatibleProvider {
    fn apply_auth_header(
        &self,
        req: reqwest::RequestBuilder,
        api_key: &str,
    ) -> reqwest::RequestBuilder {
        match &self.auth_header {
            AuthStyle::Bearer => req.header("Authorization", format!("Bearer {api_key}")),
            AuthStyle::XApiKey => req.header("x-api-key", api_key),
            AuthStyle::Custom(header) => req.header(header, api_key),
        }
    }

    async fn chat_via_responses(
        &self,
        api_key: &str,
        system_prompt: Option<&str>,
        message: &str,
        model: &str,
    ) -> anyhow::Result<String> {
        let request = ResponsesRequest {
            model: model.to_string(),
            input: vec![ResponsesInput {
                role: "user".to_string(),
                content: message.to_string(),
            }],
            instructions: system_prompt.map(str::to_string),
            stream: Some(false),
        };

        let url = self.responses_url();

        let response = self
            .apply_auth_header(self.client.post(&url).json(&request), api_key)
            .send()
            .await?;

        if !response.status().is_success() {
            let error = response.text().await?;
            anyhow::bail!("{} Responses API error: {error}", self.name);
        }

        let responses: ResponsesResponse = response.json().await?;

        extract_responses_text(responses)
            .ok_or_else(|| anyhow::anyhow!("No response from {} Responses API", self.name))
    }
}

#[async_trait]
impl Provider for OpenAiCompatibleProvider {
    async fn chat_with_system(
        &self,
        system_prompt: Option<&str>,
        message: &str,
        model: &str,
        temperature: f64,
    ) -> anyhow::Result<String> {
        let api_key = self.api_key.as_ref().ok_or_else(|| {
            anyhow::anyhow!(
                "{} API key not set. Run `zeroclaw onboard` or set the appropriate env var.",
                self.name
            )
        })?;

        let mut messages = Vec::new();

        if let Some(sys) = system_prompt {
            messages.push(Message {
                role: "system".to_string(),
                content: sys.to_string(),
            });
        }

        messages.push(Message {
            role: "user".to_string(),
            content: message.to_string(),
        });

        let request = ChatRequest {
            model: model.to_string(),
            messages,
            temperature,
            stream: Some(false),
        };

        let url = self.chat_completions_url();

        let response = self
            .apply_auth_header(self.client.post(&url).json(&request), api_key)
            .send()
            .await?;

        if !response.status().is_success() {
            let status = response.status();
            let error = response.text().await?;
            let sanitized = super::sanitize_api_error(&error);

            if status == reqwest::StatusCode::NOT_FOUND && self.supports_responses_fallback {
                return self
                    .chat_via_responses(api_key, system_prompt, message, model)
                    .await
                    .map_err(|responses_err| {
                        anyhow::anyhow!(
                            "{} API error ({status}): {sanitized} (chat completions unavailable; responses fallback failed: {responses_err})",
                            self.name
                        )
                    });
            }

            anyhow::bail!("{} API error ({status}): {sanitized}", self.name);
        }

        let chat_response: ApiChatResponse = response.json().await?;

        chat_response
            .choices
            .into_iter()
            .next()
            .map(|c| {
                // If tool_calls are present, serialize the full message as JSON
                // so parse_tool_calls can handle the OpenAI-style format
                if c.message.tool_calls.is_some()
                    && c.message
                        .tool_calls
                        .as_ref()
                        .map_or(false, |t| !t.is_empty())
                {
                    serde_json::to_string(&c.message)
                        .unwrap_or_else(|_| c.message.content.unwrap_or_default())
                } else {
                    // No tool calls, return content as-is
                    c.message.content.unwrap_or_default()
                }
            })
            .ok_or_else(|| anyhow::anyhow!("No response from {}", self.name))
    }

    async fn chat_with_history(
        &self,
        messages: &[ChatMessage],
        model: &str,
        temperature: f64,
    ) -> anyhow::Result<String> {
        let api_key = self.api_key.as_ref().ok_or_else(|| {
            anyhow::anyhow!(
                "{} API key not set. Run `zeroclaw onboard` or set the appropriate env var.",
                self.name
            )
        })?;

        let api_messages: Vec<Message> = messages
            .iter()
            .map(|m| Message {
                role: m.role.clone(),
                content: m.content.clone(),
            })
            .collect();

        let request = ChatRequest {
            model: model.to_string(),
            messages: api_messages,
            temperature,
            stream: Some(false),
        };

        let url = self.chat_completions_url();
        let response = self
            .apply_auth_header(self.client.post(&url).json(&request), api_key)
            .send()
            .await?;

        if !response.status().is_success() {
            let status = response.status();

            // Mirror chat_with_system: 404 may mean this provider uses the Responses API
            if status == reqwest::StatusCode::NOT_FOUND && self.supports_responses_fallback {
                // Extract system prompt and last user message for responses fallback
                let system = messages.iter().find(|m| m.role == "system");
                let last_user = messages.iter().rfind(|m| m.role == "user");
                if let Some(user_msg) = last_user {
                    return self
                        .chat_via_responses(
                            api_key,
                            system.map(|m| m.content.as_str()),
                            &user_msg.content,
                            model,
                        )
                        .await
                        .map_err(|responses_err| {
                            anyhow::anyhow!(
                                "{} API error (chat completions unavailable; responses fallback failed: {responses_err})",
                                self.name
                            )
                        });
                }
            }

            return Err(super::api_error(&self.name, response).await);
        }

        let chat_response: ApiChatResponse = response.json().await?;

        chat_response
            .choices
            .into_iter()
            .next()
            .map(|c| {
                // If tool_calls are present, serialize the full message as JSON
                // so parse_tool_calls can handle the OpenAI-style format
                if c.message.tool_calls.is_some()
                    && c.message
                        .tool_calls
                        .as_ref()
                        .map_or(false, |t| !t.is_empty())
                {
                    serde_json::to_string(&c.message)
                        .unwrap_or_else(|_| c.message.content.unwrap_or_default())
                } else {
                    // No tool calls, return content as-is
                    c.message.content.unwrap_or_default()
                }
            })
            .ok_or_else(|| anyhow::anyhow!("No response from {}", self.name))
    }

    async fn chat(
        &self,
        request: ProviderChatRequest<'_>,
        model: &str,
        temperature: f64,
    ) -> anyhow::Result<ProviderChatResponse> {
        let text = self
            .chat_with_history(request.messages, model, temperature)
            .await?;

        // Backward compatible path: chat_with_history may serialize tool_calls JSON into content.
        if let Ok(message) = serde_json::from_str::<ResponseMessage>(&text) {
            let tool_calls = message
                .tool_calls
                .unwrap_or_default()
                .into_iter()
                .filter_map(|tc| {
                    let function = tc.function?;
                    let name = function.name?;
                    let arguments = function.arguments.unwrap_or_else(|| "{}".to_string());
                    Some(ProviderToolCall {
                        id: uuid::Uuid::new_v4().to_string(),
                        name,
                        arguments,
                    })
                })
                .collect::<Vec<_>>();

            return Ok(ProviderChatResponse {
                text: message.content,
                tool_calls,
            });
        }

        Ok(ProviderChatResponse {
            text: Some(text),
            tool_calls: vec![],
        })
    }

    fn supports_native_tools(&self) -> bool {
        true
    }

    fn supports_streaming(&self) -> bool {
        true
    }

    fn stream_chat_with_system(
        &self,
        system_prompt: Option<&str>,
        message: &str,
        model: &str,
        temperature: f64,
        options: StreamOptions,
    ) -> stream::BoxStream<'static, StreamResult<StreamChunk>> {
        let api_key = match self.api_key.as_ref() {
            Some(key) => key.clone(),
            None => {
                let provider_name = self.name.clone();
                return stream::once(async move {
                    Err(StreamError::Provider(format!(
                        "{} API key not set",
                        provider_name
                    )))
                })
                .boxed();
            }
        };

        let mut messages = Vec::new();
        if let Some(sys) = system_prompt {
            messages.push(Message {
                role: "system".to_string(),
                content: sys.to_string(),
            });
        }
        messages.push(Message {
            role: "user".to_string(),
            content: message.to_string(),
        });

        let request = ChatRequest {
            model: model.to_string(),
            messages,
            temperature,
            stream: Some(options.enabled),
        };

        let url = self.chat_completions_url();
        let client = self.client.clone();
        let auth_header = self.auth_header.clone();

        // Use a channel to bridge the async HTTP response to the stream
        let (tx, rx) = tokio::sync::mpsc::channel::<StreamResult<StreamChunk>>(100);

        tokio::spawn(async move {
            // Build request with auth
            let mut req_builder = client.post(&url).json(&request);

            // Apply auth header
            req_builder = match &auth_header {
                AuthStyle::Bearer => {
                    req_builder.header("Authorization", format!("Bearer {}", api_key))
                }
                AuthStyle::XApiKey => req_builder.header("x-api-key", &api_key),
                AuthStyle::Custom(header) => req_builder.header(header, &api_key),
            };

            // Set accept header for streaming
            req_builder = req_builder.header("Accept", "text/event-stream");

            // Send request
            let response = match req_builder.send().await {
                Ok(r) => r,
                Err(e) => {
                    let _ = tx.send(Err(StreamError::Http(e))).await;
                    return;
                }
            };

            // Check status
            if !response.status().is_success() {
                let status = response.status();
                let error = match response.text().await {
                    Ok(e) => e,
                    Err(_) => format!("HTTP error: {}", status),
                };
                let _ = tx
                    .send(Err(StreamError::Provider(format!("{}: {}", status, error))))
                    .await;
                return;
            }

            // Convert to chunk stream and forward to channel
            let mut chunk_stream = sse_bytes_to_chunks(response, options.count_tokens).await;
            while let Some(chunk) = chunk_stream.next().await {
                if tx.send(chunk).await.is_err() {
                    break; // Receiver dropped
                }
            }
        });

        // Convert channel receiver to stream
        stream::unfold(rx, |mut rx| async move {
            match rx.recv().await {
                Some(chunk) => Some((chunk, rx)),
                None => None,
            }
        })
        .boxed()
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    fn make_provider(name: &str, url: &str, key: Option<&str>) -> OpenAiCompatibleProvider {
        OpenAiCompatibleProvider::new(name, url, key, AuthStyle::Bearer)
    }

    #[test]
    fn creates_with_key() {
        let p = make_provider("venice", "https://api.venice.ai", Some("vn-key"));
        assert_eq!(p.name, "venice");
        assert_eq!(p.base_url, "https://api.venice.ai");
        assert_eq!(p.api_key.as_deref(), Some("vn-key"));
    }

    #[test]
    fn creates_without_key() {
        let p = make_provider("test", "https://example.com", None);
        assert!(p.api_key.is_none());
    }

    #[test]
    fn strips_trailing_slash() {
        let p = make_provider("test", "https://example.com/", None);
        assert_eq!(p.base_url, "https://example.com");
    }

    #[tokio::test]
    async fn chat_fails_without_key() {
        let p = make_provider("Venice", "https://api.venice.ai", None);
        let result = p
            .chat_with_system(None, "hello", "llama-3.3-70b", 0.7)
            .await;
        assert!(result.is_err());
        assert!(result
            .unwrap_err()
            .to_string()
            .contains("Venice API key not set"));
    }

    #[test]
    fn request_serializes_correctly() {
        let req = ChatRequest {
            model: "llama-3.3-70b".to_string(),
            messages: vec![
                Message {
                    role: "system".to_string(),
                    content: "You are ZeroClaw".to_string(),
                },
                Message {
                    role: "user".to_string(),
                    content: "hello".to_string(),
                },
            ],
            temperature: 0.4,
            stream: Some(false),
        };
        let json = serde_json::to_string(&req).unwrap();
        assert!(json.contains("llama-3.3-70b"));
        assert!(json.contains("system"));
        assert!(json.contains("user"));
    }

    #[test]
    fn response_deserializes() {
        let json = r#"{"choices":[{"message":{"content":"Hello from Venice!"}}]}"#;
        let resp: ApiChatResponse = serde_json::from_str(json).unwrap();
        assert_eq!(
            resp.choices[0].message.content,
            Some("Hello from Venice!".to_string())
        );
    }

    #[test]
    fn response_empty_choices() {
        let json = r#"{"choices":[]}"#;
        let resp: ApiChatResponse = serde_json::from_str(json).unwrap();
        assert!(resp.choices.is_empty());
    }

    #[test]
    fn x_api_key_auth_style() {
        let p = OpenAiCompatibleProvider::new(
            "moonshot",
            "https://api.moonshot.cn",
            Some("ms-key"),
            AuthStyle::XApiKey,
        );
        assert!(matches!(p.auth_header, AuthStyle::XApiKey));
    }

    #[test]
    fn custom_auth_style() {
        let p = OpenAiCompatibleProvider::new(
            "custom",
            "https://api.example.com",
            Some("key"),
            AuthStyle::Custom("X-Custom-Key".into()),
        );
        assert!(matches!(p.auth_header, AuthStyle::Custom(_)));
    }

    #[tokio::test]
    async fn all_compatible_providers_fail_without_key() {
        let providers = vec![
            make_provider("Venice", "https://api.venice.ai", None),
            make_provider("Moonshot", "https://api.moonshot.cn", None),
            make_provider("GLM", "https://open.bigmodel.cn", None),
            make_provider("MiniMax", "https://api.minimaxi.com/v1", None),
            make_provider("Groq", "https://api.groq.com/openai", None),
            make_provider("Mistral", "https://api.mistral.ai", None),
            make_provider("xAI", "https://api.x.ai", None),
        ];

        for p in providers {
            let result = p.chat_with_system(None, "test", "model", 0.7).await;
            assert!(result.is_err(), "{} should fail without key", p.name);
            assert!(
                result.unwrap_err().to_string().contains("API key not set"),
                "{} error should mention key",
                p.name
            );
        }
    }

    #[test]
    fn responses_extracts_top_level_output_text() {
        let json = r#"{"output_text":"Hello from top-level","output":[]}"#;
        let response: ResponsesResponse = serde_json::from_str(json).unwrap();
        assert_eq!(
            extract_responses_text(response).as_deref(),
            Some("Hello from top-level")
        );
    }

    #[test]
    fn responses_extracts_nested_output_text() {
        let json =
            r#"{"output":[{"content":[{"type":"output_text","text":"Hello from nested"}]}]}"#;
        let response: ResponsesResponse = serde_json::from_str(json).unwrap();
        assert_eq!(
            extract_responses_text(response).as_deref(),
            Some("Hello from nested")
        );
    }

    #[test]
    fn responses_extracts_any_text_as_fallback() {
        let json = r#"{"output":[{"content":[{"type":"message","text":"Fallback text"}]}]}"#;
        let response: ResponsesResponse = serde_json::from_str(json).unwrap();
        assert_eq!(
            extract_responses_text(response).as_deref(),
            Some("Fallback text")
        );
    }

    // ══════════════════════════════════════════════════════════
    // Custom endpoint path tests (Issue #114)
    // ══════════════════════════════════════════════════════════

    #[test]
    fn chat_completions_url_standard_openai() {
        // Standard OpenAI-compatible providers get /chat/completions appended
        let p = make_provider("openai", "https://api.openai.com/v1", None);
        assert_eq!(
            p.chat_completions_url(),
            "https://api.openai.com/v1/chat/completions"
        );
    }

    #[test]
    fn chat_completions_url_trailing_slash() {
        // Trailing slash is stripped, then /chat/completions appended
        let p = make_provider("test", "https://api.example.com/v1/", None);
        assert_eq!(
            p.chat_completions_url(),
            "https://api.example.com/v1/chat/completions"
        );
    }

    #[test]
    fn chat_completions_url_volcengine_ark() {
        // VolcEngine ARK uses custom path - should use as-is
        let p = make_provider(
            "volcengine",
            "https://ark.cn-beijing.volces.com/api/coding/v3/chat/completions",
            None,
        );
        assert_eq!(
            p.chat_completions_url(),
            "https://ark.cn-beijing.volces.com/api/coding/v3/chat/completions"
        );
    }

    #[test]
    fn chat_completions_url_custom_full_endpoint() {
        // Custom provider with full endpoint path
        let p = make_provider(
            "custom",
            "https://my-api.example.com/v2/llm/chat/completions",
            None,
        );
        assert_eq!(
            p.chat_completions_url(),
            "https://my-api.example.com/v2/llm/chat/completions"
        );
    }

    #[test]
    fn chat_completions_url_requires_exact_suffix_match() {
        let p = make_provider(
            "custom",
            "https://my-api.example.com/v2/llm/chat/completions-proxy",
            None,
        );
        assert_eq!(
            p.chat_completions_url(),
            "https://my-api.example.com/v2/llm/chat/completions-proxy/chat/completions"
        );
    }

    #[test]
    fn responses_url_standard() {
        // Standard providers get /v1/responses appended
        let p = make_provider("test", "https://api.example.com", None);
        assert_eq!(p.responses_url(), "https://api.example.com/v1/responses");
    }

    #[test]
    fn responses_url_custom_full_endpoint() {
        // Custom provider with full responses endpoint
        let p = make_provider(
            "custom",
            "https://my-api.example.com/api/v2/responses",
            None,
        );
        assert_eq!(
            p.responses_url(),
            "https://my-api.example.com/api/v2/responses"
        );
    }

    #[test]
    fn responses_url_requires_exact_suffix_match() {
        let p = make_provider(
            "custom",
            "https://my-api.example.com/api/v2/responses-proxy",
            None,
        );
        assert_eq!(
            p.responses_url(),
            "https://my-api.example.com/api/v2/responses-proxy/responses"
        );
    }

    #[test]
    fn responses_url_derives_from_chat_endpoint() {
        let p = make_provider(
            "custom",
            "https://my-api.example.com/api/v2/chat/completions",
            None,
        );
        assert_eq!(
            p.responses_url(),
            "https://my-api.example.com/api/v2/responses"
        );
    }

    #[test]
    fn responses_url_base_with_v1_no_duplicate() {
        let p = make_provider("test", "https://api.example.com/v1", None);
        assert_eq!(p.responses_url(), "https://api.example.com/v1/responses");
    }

    #[test]
    fn responses_url_non_v1_api_path_uses_raw_suffix() {
        let p = make_provider("test", "https://api.example.com/api/coding/v3", None);
        assert_eq!(
            p.responses_url(),
            "https://api.example.com/api/coding/v3/responses"
        );
    }

    #[test]
    fn chat_completions_url_without_v1() {
        // Provider configured without /v1 in base URL
        let p = make_provider("test", "https://api.example.com", None);
        assert_eq!(
            p.chat_completions_url(),
            "https://api.example.com/chat/completions"
        );
    }

    #[test]
    fn chat_completions_url_base_with_v1() {
        // Provider configured with /v1 in base URL
        let p = make_provider("test", "https://api.example.com/v1", None);
        assert_eq!(
            p.chat_completions_url(),
            "https://api.example.com/v1/chat/completions"
        );
    }

    // ══════════════════════════════════════════════════════════
    // Provider-specific endpoint tests (Issue #167)
    // ══════════════════════════════════════════════════════════

    #[test]
    fn chat_completions_url_zai() {
        // Z.AI uses /api/paas/v4 base path
        let p = make_provider("zai", "https://api.z.ai/api/paas/v4", None);
        assert_eq!(
            p.chat_completions_url(),
            "https://api.z.ai/api/paas/v4/chat/completions"
        );
    }

    #[test]
    fn chat_completions_url_minimax() {
        // MiniMax OpenAI-compatible endpoint requires /v1 base path.
        let p = make_provider("minimax", "https://api.minimaxi.com/v1", None);
        assert_eq!(
            p.chat_completions_url(),
            "https://api.minimaxi.com/v1/chat/completions"
        );
    }

    #[test]
    fn chat_completions_url_glm() {
        // GLM (BigModel) uses /api/paas/v4 base path
        let p = make_provider("glm", "https://open.bigmodel.cn/api/paas/v4", None);
        assert_eq!(
            p.chat_completions_url(),
            "https://open.bigmodel.cn/api/paas/v4/chat/completions"
        );
    }

    #[test]
    fn chat_completions_url_opencode() {
        // OpenCode Zen uses /zen/v1 base path
        let p = make_provider("opencode", "https://opencode.ai/zen/v1", None);
        assert_eq!(
            p.chat_completions_url(),
            "https://opencode.ai/zen/v1/chat/completions"
        );
    }
}