use crate::error::WhisperError;
use crate::WhisperToken;
use std::ffi::{c_int, CStr, CString};

/// Safe Rust wrapper around a Whisper context.
///
/// You likely want to create this with [WhisperInnerContext::new_with_params],
/// create a state with [WhisperInnerContext::create_state],
/// then run a full transcription with [WhisperState::full].
#[derive(Debug)]
pub struct WhisperInnerContext {
    pub(crate) ctx: *mut whisper_rs_sys::whisper_context,
}

impl WhisperInnerContext {
    /// Create a new WhisperContext from a file, with parameters.
    ///
    /// # Arguments
    /// * path: The path to the model file.
    /// * parameters: A parameter struct containing the parameters to use.
    ///
    /// # Returns
    /// Ok(Self) on success, Err(WhisperError) on failure.
    ///
    /// # C++ equivalent
    /// `struct whisper_context * whisper_init_from_file_with_params_no_state(const char * path_model, struct whisper_context_params params);`
    pub fn new_with_params(
        path: &str,
        parameters: WhisperContextParameters,
    ) -> Result<Self, WhisperError> {
        let path_cstr = CString::new(path)?;
        let ctx = unsafe {
            whisper_rs_sys::whisper_init_from_file_with_params_no_state(
                path_cstr.as_ptr(),
                parameters.to_c_struct(),
            )
        };
        if ctx.is_null() {
            Err(WhisperError::InitError)
        } else {
            Ok(Self { ctx })
        }
    }

    /// Create a new WhisperContext from a buffer.
    ///
    /// # Arguments
    /// * buffer: The buffer containing the model.
    ///
    /// # Returns
    /// Ok(Self) on success, Err(WhisperError) on failure.
    ///
    /// # C++ equivalent
    /// `struct whisper_context * whisper_init_from_buffer_with_params_no_state(void * buffer, size_t buffer_size, struct whisper_context_params params);`
    pub fn new_from_buffer_with_params(
        buffer: &[u8],
        parameters: WhisperContextParameters,
    ) -> Result<Self, WhisperError> {
        let ctx = unsafe {
            whisper_rs_sys::whisper_init_from_buffer_with_params_no_state(
                buffer.as_ptr() as _,
                buffer.len(),
                parameters.to_c_struct(),
            )
        };
        if ctx.is_null() {
            Err(WhisperError::InitError)
        } else {
            Ok(Self { ctx })
        }
    }

    /// Convert the provided text into tokens.
    ///
    /// # Arguments
    /// * text: The text to convert.
    ///
    /// # Returns
    /// `Ok(Vec<WhisperToken>)` on success, `Err(WhisperError)` on failure.
    ///
    /// # C++ equivalent
    /// `int whisper_tokenize(struct whisper_context * ctx, const char * text, whisper_token * tokens, int n_max_tokens);`
    pub fn tokenize(
        &self,
        text: &str,
        max_tokens: usize,
    ) -> Result<Vec<WhisperToken>, WhisperError> {
        // convert the text to a nul-terminated C string. Will raise an error if the text contains
        // any nul bytes.
        let text = CString::new(text)?;
        // allocate at least max_tokens to ensure the memory is valid
        let mut tokens: Vec<WhisperToken> = Vec::with_capacity(max_tokens);
        let ret = unsafe {
            whisper_rs_sys::whisper_tokenize(
                self.ctx,
                text.as_ptr(),
                tokens.as_mut_ptr(),
                max_tokens as c_int,
            )
        };
        if ret == -1 {
            Err(WhisperError::InvalidText)
        } else {
            // SAFETY: when ret != -1, we know that the length of the vector is at least ret tokens
            unsafe { tokens.set_len(ret as usize) };
            Ok(tokens)
        }
    }

    /// Get n_vocab.
    ///
    /// # Returns
    /// c_int
    ///
    /// # C++ equivalent
    /// `int whisper_n_vocab        (struct whisper_context * ctx)`
    #[inline]
    pub fn n_vocab(&self) -> c_int {
        unsafe { whisper_rs_sys::whisper_n_vocab(self.ctx) }
    }

    /// Get n_text_ctx.
    ///
    /// # Returns
    /// c_int
    ///
    /// # C++ equivalent
    /// `int whisper_n_text_ctx     (struct whisper_context * ctx);`
    #[inline]
    pub fn n_text_ctx(&self) -> c_int {
        unsafe { whisper_rs_sys::whisper_n_text_ctx(self.ctx) }
    }

    /// Get n_audio_ctx.
    ///
    /// # Returns
    /// c_int
    ///
    /// # C++ equivalent
    /// `int whisper_n_audio_ctx     (struct whisper_context * ctx);`
    #[inline]
    pub fn n_audio_ctx(&self) -> c_int {
        unsafe { whisper_rs_sys::whisper_n_audio_ctx(self.ctx) }
    }

    /// Does this model support multiple languages?
    ///
    /// # C++ equivalent
    /// `int whisper_is_multilingual(struct whisper_context * ctx)`
    #[inline]
    pub fn is_multilingual(&self) -> bool {
        unsafe { whisper_rs_sys::whisper_is_multilingual(self.ctx) != 0 }
    }

    /// Get model_n_vocab.
    ///
    /// # Returns
    /// c_int
    ///
    /// # C++ equivalent
    /// `int whisper_model_n_vocab      (struct whisper_context * ctx);`
    #[inline]
    pub fn model_n_vocab(&self) -> c_int {
        unsafe { whisper_rs_sys::whisper_model_n_vocab(self.ctx) }
    }

    /// Get model_n_audio_ctx.
    ///
    /// # Returns
    /// c_int
    ///
    /// # C++ equivalent
    /// `int whisper_model_n_audio_ctx    (struct whisper_context * ctx)`
    #[inline]
    pub fn model_n_audio_ctx(&self) -> c_int {
        unsafe { whisper_rs_sys::whisper_model_n_audio_ctx(self.ctx) }
    }

    /// Get model_n_audio_state.
    ///
    /// # Returns
    /// c_int
    ///
    /// # C++ equivalent
    /// `int whisper_model_n_audio_state(struct whisper_context * ctx);`
    #[inline]
    pub fn model_n_audio_state(&self) -> c_int {
        unsafe { whisper_rs_sys::whisper_model_n_audio_state(self.ctx) }
    }

    /// Get model_n_audio_head.
    ///
    /// # Returns
    /// c_int
    ///
    /// # C++ equivalent
    /// `int whisper_model_n_audio_head (struct whisper_context * ctx);`
    #[inline]
    pub fn model_n_audio_head(&self) -> c_int {
        unsafe { whisper_rs_sys::whisper_model_n_audio_head(self.ctx) }
    }

    /// Get model_n_audio_layer.
    ///
    /// # Returns
    /// c_int
    ///
    /// # C++ equivalent
    /// `int whisper_model_n_audio_layer(struct whisper_context * ctx);`
    #[inline]
    pub fn model_n_audio_layer(&self) -> c_int {
        unsafe { whisper_rs_sys::whisper_model_n_audio_layer(self.ctx) }
    }

    /// Get model_n_text_ctx.
    ///
    /// # Returns
    /// c_int
    ///
    /// # C++ equivalent
    /// `int whisper_model_n_text_ctx     (struct whisper_context * ctx)`
    #[inline]
    pub fn model_n_text_ctx(&self) -> c_int {
        unsafe { whisper_rs_sys::whisper_model_n_text_ctx(self.ctx) }
    }

    /// Get model_n_text_state.
    ///
    /// # Returns
    /// c_int
    ///
    /// # C++ equivalent
    /// `int whisper_model_n_text_state (struct whisper_context * ctx);`
    #[inline]
    pub fn model_n_text_state(&self) -> c_int {
        unsafe { whisper_rs_sys::whisper_model_n_text_state(self.ctx) }
    }

    /// Get model_n_text_head.
    ///
    /// # Returns
    /// c_int
    ///
    /// # C++ equivalent
    /// `int whisper_model_n_text_head  (struct whisper_context * ctx);`
    #[inline]
    pub fn model_n_text_head(&self) -> c_int {
        unsafe { whisper_rs_sys::whisper_model_n_text_head(self.ctx) }
    }

    /// Get model_n_text_layer.
    ///
    /// # Returns
    /// c_int
    ///
    /// # C++ equivalent
    /// `int whisper_model_n_text_layer (struct whisper_context * ctx);`
    #[inline]
    pub fn model_n_text_layer(&self) -> c_int {
        unsafe { whisper_rs_sys::whisper_model_n_text_layer(self.ctx) }
    }

    /// Get model_n_mels.
    ///
    /// # Returns
    /// c_int
    ///
    /// # C++ equivalent
    /// `int whisper_model_n_mels       (struct whisper_context * ctx);`
    #[inline]
    pub fn model_n_mels(&self) -> c_int {
        unsafe { whisper_rs_sys::whisper_model_n_mels(self.ctx) }
    }

    /// Get model_ftype.
    ///
    /// # Returns
    /// c_int
    ///
    /// # C++ equivalent
    /// `int whisper_model_ftype          (struct whisper_context * ctx);`
    #[inline]
    pub fn model_ftype(&self) -> c_int {
        unsafe { whisper_rs_sys::whisper_model_ftype(self.ctx) }
    }

    /// Get model_type.
    ///
    /// # Returns
    /// c_int
    ///
    /// # C++ equivalent
    /// `int whisper_model_type         (struct whisper_context * ctx);`
    #[inline]
    pub fn model_type(&self) -> c_int {
        unsafe { whisper_rs_sys::whisper_model_type(self.ctx) }
    }

    // token functions
    /// Convert a token ID to a string.
    ///
    /// # Arguments
    /// * token_id: ID of the token.
    ///
    /// # Returns
    /// Ok(&str) on success, Err(WhisperError) on failure.
    ///
    /// # C++ equivalent
    /// `const char * whisper_token_to_str(struct whisper_context * ctx, whisper_token token)`
    pub fn token_to_str(&self, token_id: WhisperToken) -> Result<&str, WhisperError> {
        let c_str = self.token_to_cstr(token_id)?;
        let r_str = c_str.to_str()?;
        Ok(r_str)
    }

    /// Convert a token ID to a &CStr.
    ///
    /// # Arguments
    /// * token_id: ID of the token.
    ///
    /// # Returns
    /// Ok(String) on success, Err(WhisperError) on failure.
    ///
    /// # C++ equivalent
    /// `const char * whisper_token_to_str(struct whisper_context * ctx, whisper_token token)`
    pub fn token_to_cstr(&self, token_id: WhisperToken) -> Result<&CStr, WhisperError> {
        let ret = unsafe { whisper_rs_sys::whisper_token_to_str(self.ctx, token_id) };
        if ret.is_null() {
            return Err(WhisperError::NullPointer);
        }
        Ok(unsafe { CStr::from_ptr(ret) })
    }

    /// Undocumented but exposed function in the C++ API.
    /// `const char * whisper_model_type_readable(struct whisper_context * ctx);`
    ///
    /// # Returns
    /// Ok(String) on success, Err(WhisperError) on failure.
    pub fn model_type_readable(&self) -> Result<String, WhisperError> {
        let ret = unsafe { whisper_rs_sys::whisper_model_type_readable(self.ctx) };
        if ret.is_null() {
            return Err(WhisperError::NullPointer);
        }
        let c_str = unsafe { CStr::from_ptr(ret) };
        let r_str = c_str.to_str()?;
        Ok(r_str.to_string())
    }

    /// Get the ID of the eot token.
    ///
    /// # C++ equivalent
    /// `whisper_token whisper_token_eot (struct whisper_context * ctx)`
    #[inline]
    pub fn token_eot(&self) -> WhisperToken {
        unsafe { whisper_rs_sys::whisper_token_eot(self.ctx) }
    }

    /// Get the ID of the sot token.
    ///
    /// # C++ equivalent
    /// `whisper_token whisper_token_sot (struct whisper_context * ctx)`
    #[inline]
    pub fn token_sot(&self) -> WhisperToken {
        unsafe { whisper_rs_sys::whisper_token_sot(self.ctx) }
    }

    /// Get the ID of the solm token.
    ///
    /// # C++ equivalent
    /// `whisper_token whisper_token_solm(struct whisper_context * ctx)`
    #[inline]
    pub fn token_solm(&self) -> WhisperToken {
        unsafe { whisper_rs_sys::whisper_token_solm(self.ctx) }
    }

    /// Get the ID of the prev token.
    ///
    /// # C++ equivalent
    /// `whisper_token whisper_token_prev(struct whisper_context * ctx)`
    #[inline]
    pub fn token_prev(&self) -> WhisperToken {
        unsafe { whisper_rs_sys::whisper_token_prev(self.ctx) }
    }

    /// Get the ID of the nosp token.
    ///
    /// # C++ equivalent
    /// `whisper_token whisper_token_nosp(struct whisper_context * ctx)`
    #[inline]
    pub fn token_nosp(&self) -> WhisperToken {
        unsafe { whisper_rs_sys::whisper_token_nosp(self.ctx) }
    }

    /// Get the ID of the not token.
    ///
    /// # C++ equivalent
    /// `whisper_token whisper_token_not (struct whisper_context * ctx)`
    #[inline]
    pub fn token_not(&self) -> WhisperToken {
        unsafe { whisper_rs_sys::whisper_token_not(self.ctx) }
    }

    /// Get the ID of the beg token.
    ///
    /// # C++ equivalent
    /// `whisper_token whisper_token_beg (struct whisper_context * ctx)`
    #[inline]
    pub fn token_beg(&self) -> WhisperToken {
        unsafe { whisper_rs_sys::whisper_token_beg(self.ctx) }
    }

    /// Get the ID of a specified language token
    ///
    /// # Arguments
    /// * lang_id: ID of the language
    ///
    /// # C++ equivalent
    /// `whisper_token whisper_token_lang(struct whisper_context * ctx, int lang_id)`
    #[inline]
    pub fn token_lang(&self, lang_id: c_int) -> WhisperToken {
        unsafe { whisper_rs_sys::whisper_token_lang(self.ctx, lang_id) }
    }

    /// Print performance statistics to stderr.
    ///
    /// # C++ equivalent
    /// `void whisper_print_timings(struct whisper_context * ctx)`
    #[inline]
    pub fn print_timings(&self) {
        unsafe { whisper_rs_sys::whisper_print_timings(self.ctx) }
    }

    /// Reset performance statistics.
    ///
    /// # C++ equivalent
    /// `void whisper_reset_timings(struct whisper_context * ctx)`
    #[inline]
    pub fn reset_timings(&self) {
        unsafe { whisper_rs_sys::whisper_reset_timings(self.ctx) }
    }

    // task tokens
    /// Get the ID of the translate task token.
    ///
    /// # C++ equivalent
    /// `whisper_token whisper_token_translate ()`
    pub fn token_translate(&self) -> WhisperToken {
        unsafe { whisper_rs_sys::whisper_token_translate(self.ctx) }
    }

    /// Get the ID of the transcribe task token.
    ///
    /// # C++ equivalent
    /// `whisper_token whisper_token_transcribe()`
    pub fn token_transcribe(&self) -> WhisperToken {
        unsafe { whisper_rs_sys::whisper_token_transcribe(self.ctx) }
    }
}

impl Drop for WhisperInnerContext {
    #[inline]
    fn drop(&mut self) {
        unsafe { whisper_rs_sys::whisper_free(self.ctx) };
    }
}

// following implementations are safe
// see https://github.com/ggerganov/whisper.cpp/issues/32#issuecomment-1272790388
unsafe impl Send for WhisperInnerContext {}
unsafe impl Sync for WhisperInnerContext {}

pub struct WhisperContextParameters<'a> {
    /// Use GPU if available.
    ///
    /// **Warning**: Does not have an effect if OpenCL is selected as GPU backend
    /// (in that case, GPU is always enabled).
    pub use_gpu: bool,
    /// Enable flash attention, default false
    ///
    /// **Warning** Can't be used with DTW. DTW will be disabled if flash_attn is true
    pub flash_attn: bool,
    /// GPU device id, default 0
    pub gpu_device: c_int,
    /// DTW token level timestamp parameters
    pub dtw_parameters: DtwParameters<'a>,
}

#[allow(clippy::derivable_impls)] // this impl cannot be derived
impl<'a> Default for WhisperContextParameters<'a> {
    fn default() -> Self {
        Self {
            use_gpu: cfg!(feature = "_gpu"),
            flash_attn: false,
            gpu_device: 0,
            dtw_parameters: DtwParameters::default(),
        }
    }
}
impl<'a> WhisperContextParameters<'a> {
    pub fn new() -> Self {
        Self::default()
    }
    pub fn use_gpu(&mut self, use_gpu: bool) -> &mut Self {
        self.use_gpu = use_gpu;
        self
    }
    pub fn flash_attn(&mut self, flash_attn: bool) -> &mut Self {
        self.flash_attn = flash_attn;
        self
    }
    pub fn gpu_device(&mut self, gpu_device: c_int) -> &mut Self {
        self.gpu_device = gpu_device;
        self
    }
    pub fn dtw_parameters(&mut self, dtw_parameters: DtwParameters<'a>) -> &mut Self {
        self.dtw_parameters = dtw_parameters;
        self
    }

    fn to_c_struct(&self) -> whisper_rs_sys::whisper_context_params {
        let dtw_token_timestamps = !matches!(self.dtw_parameters.mode, DtwMode::None);
        let mut dtw_aheads_preset =
            whisper_rs_sys::whisper_alignment_heads_preset_WHISPER_AHEADS_NONE;
        let mut dtw_n_top: c_int = -1;
        let mut dtw_aheads = whisper_rs_sys::whisper_aheads {
            n_heads: 0,
            heads: std::ptr::null(),
        };

        match &self.dtw_parameters.mode {
            DtwMode::None => {}
            DtwMode::TopMost { n_top } => {
                dtw_aheads_preset =
                    whisper_rs_sys::whisper_alignment_heads_preset_WHISPER_AHEADS_N_TOP_MOST;
                dtw_n_top = *n_top;
            }
            DtwMode::Custom { aheads } => {
                dtw_aheads_preset =
                    whisper_rs_sys::whisper_alignment_heads_preset_WHISPER_AHEADS_CUSTOM;

                dtw_aheads = whisper_rs_sys::whisper_aheads {
                    n_heads: aheads.len(),
                    heads: aheads.as_ptr(),
                };
            }
            DtwMode::ModelPreset { model_preset } => match model_preset {
                DtwModelPreset::TinyEn => {
                    dtw_aheads_preset =
                        whisper_rs_sys::whisper_alignment_heads_preset_WHISPER_AHEADS_TINY_EN;
                }
                DtwModelPreset::Tiny => {
                    dtw_aheads_preset =
                        whisper_rs_sys::whisper_alignment_heads_preset_WHISPER_AHEADS_TINY;
                }
                DtwModelPreset::BaseEn => {
                    dtw_aheads_preset =
                        whisper_rs_sys::whisper_alignment_heads_preset_WHISPER_AHEADS_BASE_EN;
                }
                DtwModelPreset::Base => {
                    dtw_aheads_preset =
                        whisper_rs_sys::whisper_alignment_heads_preset_WHISPER_AHEADS_BASE;
                }
                DtwModelPreset::SmallEn => {
                    dtw_aheads_preset =
                        whisper_rs_sys::whisper_alignment_heads_preset_WHISPER_AHEADS_SMALL_EN;
                }
                DtwModelPreset::Small => {
                    dtw_aheads_preset =
                        whisper_rs_sys::whisper_alignment_heads_preset_WHISPER_AHEADS_SMALL;
                }
                DtwModelPreset::MediumEn => {
                    dtw_aheads_preset =
                        whisper_rs_sys::whisper_alignment_heads_preset_WHISPER_AHEADS_MEDIUM_EN;
                }
                DtwModelPreset::Medium => {
                    dtw_aheads_preset =
                        whisper_rs_sys::whisper_alignment_heads_preset_WHISPER_AHEADS_MEDIUM;
                }
                DtwModelPreset::LargeV1 => {
                    dtw_aheads_preset =
                        whisper_rs_sys::whisper_alignment_heads_preset_WHISPER_AHEADS_LARGE_V1;
                }
                DtwModelPreset::LargeV2 => {
                    dtw_aheads_preset =
                        whisper_rs_sys::whisper_alignment_heads_preset_WHISPER_AHEADS_LARGE_V2;
                }
                DtwModelPreset::LargeV3 => {
                    dtw_aheads_preset =
                        whisper_rs_sys::whisper_alignment_heads_preset_WHISPER_AHEADS_LARGE_V3;
                }
            },
        }

        whisper_rs_sys::whisper_context_params {
            use_gpu: self.use_gpu,
            flash_attn: self.flash_attn,
            gpu_device: self.gpu_device,
            dtw_token_timestamps,
            dtw_aheads_preset,
            dtw_n_top,
            dtw_aheads,
            dtw_mem_size: self.dtw_parameters.dtw_mem_size,
        }
    }
}

/// [EXPERIMENTAL] Enable Token-level timestamps with DTW, default Disabled
#[derive(Debug, Clone)]
pub struct DtwParameters<'a> {
    pub mode: DtwMode<'a>,
    pub dtw_mem_size: usize,
}

impl Default for DtwParameters<'_> {
    fn default() -> Self {
        Self {
            mode: DtwMode::None,
            dtw_mem_size: 1024 * 1024 * 128,
        }
    }
}

#[derive(Debug, Clone)]
pub enum DtwMode<'a> {
    /// DTW token level timestamps disabled
    None,
    /// Use N Top Most layers from loaded model
    TopMost {
        /// Number of top text layers used from model, should be 0 < n_top <= model n_text_layer
        n_top: c_int,
    },
    /// Use custom aheads, non-empty list of whisper_ahead.
    /// 0 < n_text_layer < model n_text_layer, 0 < n_head < model n_text_head for each element
    /// See details https://github.com/ggerganov/whisper.cpp/pull/1485#discussion_r1519681143
    Custom {
        aheads: &'a [whisper_rs_sys::whisper_ahead],
    },
    /// Use predefined preset for standard models
    ModelPreset { model_preset: DtwModelPreset },
}

#[derive(Debug, Clone)]
pub enum DtwModelPreset {
    TinyEn,
    Tiny,
    BaseEn,
    Base,
    SmallEn,
    Small,
    MediumEn,
    Medium,
    LargeV1,
    LargeV2,
    LargeV3,
}

#[cfg(test)]
#[cfg(feature = "test-with-tiny-model")]
mod test_with_tiny_model {
    use super::*;
    const MODEL_PATH: &str = "./sys/whisper.cpp/models/ggml-tiny.en.bin";

    // These tests expect that the tiny.en model has been downloaded
    // using the script `sys/whisper.cpp/models/download-ggml-model.sh tiny.en`

    #[test]
    fn test_tokenize_round_trip() {
        let ctx = WhisperInnerContext::new(MODEL_PATH).expect("Download the ggml-tiny.en model using 'sys/whisper.cpp/models/download-ggml-model.sh tiny.en'");
        let text_in = " And so my fellow Americans, ask not what your country can do for you, ask what you can do for your country.";
        let tokens = ctx.tokenize(text_in, 1024).unwrap();
        let text_out = tokens
            .into_iter()
            .map(|t| ctx.token_to_str(t).unwrap())
            .collect::<Vec<_>>()
            .join("");
        assert_eq!(text_in, text_out);
    }
}