//! Chatterbox TTS engine — ONNX-based (legacy).
//!
//! This is the existing Chatterbox TTS implementation moved from `tts.rs`,
//! now implementing the `TtsEngine` trait for unified access.

use std::borrow::Cow;
use std::fs;
use std::path::{Path, PathBuf};
use std::sync::atomic::AtomicBool;
use std::sync::{Arc, Mutex};

use hf_hub::api::sync::Api;
use ndarray::{Array2, Array3, Array4, ArrayD, IxDyn};
use ort::session::Session;
use ort::value::{DynValue, Value};
use tokenizers::Tokenizer;

use crate::audio;

use super::{
    apply_repetition_penalty, argmax, resample_to_24k, AudioChunk, TtsEngine, TtsError,
    SAMPLE_RATE,
};

const START_SPEECH_TOKEN: i64 = 6561;
const STOP_SPEECH_TOKEN: i64 = 6562;
const SILENCE_TOKEN: i64 = 4299;
const NUM_LAYERS: usize = 24;
const NUM_KV_HEADS: usize = 16;
const HEAD_DIM: usize = 64;

const MODEL_ID: &str = "ResembleAI/chatterbox-turbo-ONNX";
const DEFAULT_MODEL_DIR: &str = "models/chatterbox-turbo";

struct VoiceCondition {
    audio_features: ArrayD<f32>,
    prompt_tokens: ArrayD<i64>,
    speaker_embeddings: ArrayD<f32>,
    speaker_features: ArrayD<f32>,
}

fn extract_f32_tensor(value: &Value) -> Result<ArrayD<f32>, TtsError> {
    let (shape, data) = value
        .try_extract_tensor::<f32>()
        .map_err(|e| TtsError::Inference(e.to_string()))?;

    let dims: Vec<usize> = shape.iter().map(|&d| d as usize).collect();
    ArrayD::from_shape_vec(IxDyn(&dims), data.to_vec())
        .map_err(|e| TtsError::Inference(e.to_string()))
}

fn extract_i64_tensor(value: &Value) -> Result<ArrayD<i64>, TtsError> {
    let (shape, data) = value
        .try_extract_tensor::<i64>()
        .map_err(|e| TtsError::Inference(e.to_string()))?;

    let dims: Vec<usize> = shape.iter().map(|&d| d as usize).collect();
    ArrayD::from_shape_vec(IxDyn(&dims), data.to_vec())
        .map_err(|e| TtsError::Inference(e.to_string()))
}

pub struct ChatterboxTTS {
    speech_encoder: Mutex<Session>,
    embed_tokens: Mutex<Session>,
    language_model: Mutex<Session>,
    conditional_decoder: Mutex<Session>,
    tokenizer: Tokenizer,
}

// SAFETY: Sessions are behind Mutex, Tokenizer is Send+Sync
unsafe impl Send for ChatterboxTTS {}
unsafe impl Sync for ChatterboxTTS {}

impl ChatterboxTTS {
    pub fn from_pretrained(model_dir: Option<&str>) -> Result<Self, TtsError> {
        let model_path = PathBuf::from(model_dir.unwrap_or(DEFAULT_MODEL_DIR));

        if !model_path.exists() {
            download_models(&model_path)?;
        }

        Self::load_from_path(&model_path)
    }

    pub fn load_from_path(model_dir: &Path) -> Result<Self, TtsError> {
        let speech_encoder = Session::builder()?
            .with_intra_threads(4)?
            .commit_from_file(model_dir.join("speech_encoder.onnx"))?;

        let embed_tokens = Session::builder()?
            .with_intra_threads(4)?
            .commit_from_file(model_dir.join("embed_tokens.onnx"))?;

        let language_model = Session::builder()?
            .with_intra_threads(4)?
            .commit_from_file(model_dir.join("language_model.onnx"))?;

        let conditional_decoder = Session::builder()?
            .with_intra_threads(4)?
            .commit_from_file(model_dir.join("conditional_decoder.onnx"))?;

        let tokenizer_path = model_dir.join("tokenizer.json");
        let tokenizer = Tokenizer::from_file(&tokenizer_path)
            .map_err(|e| TtsError::Tokenizer(e.to_string()))?;

        Ok(Self {
            speech_encoder: Mutex::new(speech_encoder),
            embed_tokens: Mutex::new(embed_tokens),
            language_model: Mutex::new(language_model),
            conditional_decoder: Mutex::new(conditional_decoder),
            tokenizer,
        })
    }

    pub fn generate_tts(&self) -> Result<Vec<f32>, TtsError> {
        Err(TtsError::VoiceRequired)
    }

    pub fn generate_tts_with_voice(
        &self,
        text: &str,
        sample_audio_path: &Path,
    ) -> Result<Vec<f32>, TtsError> {
        let audio = audio::to_16k_mono_from_path(sample_audio_path)?;
        let resampled = resample_to_24k(&audio.samples, audio.sample_rate);
        self.generate_tts_with_samples(text, &resampled, SAMPLE_RATE)
    }

    pub fn generate_tts_with_samples(
        &self,
        text: &str,
        samples: &[f32],
        sample_rate: u32,
    ) -> Result<Vec<f32>, TtsError> {
        let resampled = if sample_rate != SAMPLE_RATE {
            resample_to_24k(samples, sample_rate)
        } else {
            samples.to_vec()
        };

        let voice_condition = self.encode_voice(&resampled)?;

        let encoding = self
            .tokenizer
            .encode(text, true)
            .map_err(|e| TtsError::Tokenizer(e.to_string()))?;

        let text_input_ids: Vec<i64> = encoding.get_ids().iter().map(|&id| id as i64).collect();

        let generated_tokens =
            self.generate_speech_tokens(&text_input_ids, &voice_condition.audio_features)?;

        let prompt_tokens: Vec<i64> = voice_condition.prompt_tokens.iter().copied().collect();
        let silence_tokens = vec![SILENCE_TOKEN; 3];

        let mut final_tokens =
            Vec::with_capacity(prompt_tokens.len() + generated_tokens.len() + silence_tokens.len());
        final_tokens.extend_from_slice(&prompt_tokens);
        final_tokens.extend_from_slice(&generated_tokens);
        final_tokens.extend_from_slice(&silence_tokens);

        let audio_samples = self.decode_speech_tokens(
            &final_tokens,
            &voice_condition.speaker_embeddings,
            &voice_condition.speaker_features,
        )?;

        Ok(audio_samples)
    }

    fn encode_voice(&self, samples: &[f32]) -> Result<VoiceCondition, TtsError> {
        let audio_arr = Array2::from_shape_vec((1, samples.len()), samples.to_vec())
            .map_err(|e| TtsError::Inference(e.to_string()))?;

        let audio_tensor = Value::from_array(audio_arr)?;

        let mut encoder = self
            .speech_encoder
            .lock()
            .map_err(|e| TtsError::Inference(e.to_string()))?;
        let outputs = encoder.run(ort::inputs!["audio_values" => audio_tensor])?;

        let audio_features = extract_f32_tensor(&outputs[0])?;
        let prompt_tokens = extract_i64_tensor(&outputs[1])?;
        let speaker_embeddings = extract_f32_tensor(&outputs[2])?;
        let speaker_features = extract_f32_tensor(&outputs[3])?;

        Ok(VoiceCondition {
            audio_features,
            prompt_tokens,
            speaker_embeddings,
            speaker_features,
        })
    }

    fn generate_speech_tokens(
        &self,
        text_input_ids: &[i64],
        audio_features: &ArrayD<f32>,
    ) -> Result<Vec<i64>, TtsError> {
        let max_new_tokens: usize = 1024;
        let repetition_penalty: f32 = 1.2;

        let mut generate_tokens: Vec<i64> = vec![START_SPEECH_TOKEN];

        let mut past_key_values = Self::init_kv_cache(0);
        let mut first_iteration = true;
        let mut total_seq_len: usize = 0;

        for _ in 0..max_new_tokens {
            let current_input_ids = if first_iteration {
                text_input_ids.to_vec()
            } else {
                vec![*generate_tokens.last().unwrap()]
            };

            let input_ids_arr =
                Array2::from_shape_vec((1, current_input_ids.len()), current_input_ids)
                    .map_err(|e| TtsError::Inference(e.to_string()))?;

            let input_ids_tensor = Value::from_array(input_ids_arr)?;

            let inputs_embeds = {
                let mut embed = self
                    .embed_tokens
                    .lock()
                    .map_err(|e| TtsError::Inference(e.to_string()))?;
                let embed_outputs = embed.run(ort::inputs![input_ids_tensor])?;
                extract_f32_tensor(&embed_outputs[0])?
            };

            let inputs_embeds = if first_iteration {
                let audio_feat_3d = audio_features
                    .view()
                    .into_dimensionality::<ndarray::Ix3>()
                    .map_err(|e| TtsError::Inference(e.to_string()))?;
                let text_emb_3d = inputs_embeds
                    .view()
                    .into_dimensionality::<ndarray::Ix3>()
                    .map_err(|e| TtsError::Inference(e.to_string()))?;

                ndarray::concatenate(ndarray::Axis(1), &[audio_feat_3d, text_emb_3d])
                    .map_err(|e| TtsError::Inference(e.to_string()))?
            } else {
                inputs_embeds
                    .view()
                    .into_dimensionality::<ndarray::Ix3>()
                    .map_err(|e| TtsError::Inference(e.to_string()))?
                    .to_owned()
            };

            let seq_len = inputs_embeds.shape()[1];

            let (attention_mask, position_ids) = if first_iteration {
                total_seq_len = seq_len;
                let attention_mask: Array2<i64> = Array2::ones((1, seq_len));
                let position_ids = Array2::from_shape_fn((1, seq_len), |(_, j)| j as i64);
                (attention_mask, position_ids)
            } else {
                total_seq_len += 1;
                let attention_mask: Array2<i64> = Array2::ones((1, total_seq_len));
                let position_ids =
                    Array2::from_shape_vec((1, 1), vec![(total_seq_len - 1) as i64])
                        .map_err(|e| TtsError::Inference(e.to_string()))?;
                (attention_mask, position_ids)
            };

            let (logits, new_kv) = self.run_language_model(
                inputs_embeds,
                position_ids,
                attention_mask,
                past_key_values,
            )?;

            past_key_values = new_kv;

            let logits_3d = logits
                .view()
                .into_dimensionality::<ndarray::Ix3>()
                .map_err(|e| TtsError::Inference(e.to_string()))?;
            let last_idx = logits_3d.shape()[1] - 1;

            let mut current_logits: Vec<f32> = logits_3d
                .slice(ndarray::s![0, last_idx, ..])
                .iter()
                .copied()
                .collect();

            apply_repetition_penalty(&mut current_logits, &generate_tokens, repetition_penalty);

            let next_token = argmax(&current_logits);
            generate_tokens.push(next_token);

            if next_token == STOP_SPEECH_TOKEN {
                break;
            }

            first_iteration = false;
        }

        if generate_tokens.len() > 2 {
            Ok(generate_tokens[1..generate_tokens.len() - 1].to_vec())
        } else {
            Ok(Vec::new())
        }
    }

    fn init_kv_cache(seq_len: usize) -> Vec<Array4<f32>> {
        let mut cache = Vec::with_capacity(NUM_LAYERS * 2);
        for _ in 0..NUM_LAYERS {
            let key = Array4::<f32>::zeros((1, NUM_KV_HEADS, seq_len, HEAD_DIM));
            let value = Array4::<f32>::zeros((1, NUM_KV_HEADS, seq_len, HEAD_DIM));
            cache.push(key);
            cache.push(value);
        }
        cache
    }

    fn run_language_model(
        &self,
        inputs_embeds: Array3<f32>,
        position_ids: Array2<i64>,
        attention_mask: Array2<i64>,
        past_key_values: Vec<Array4<f32>>,
    ) -> Result<(ArrayD<f32>, Vec<Array4<f32>>), TtsError> {
        let mut inputs: Vec<(Cow<str>, DynValue)> = Vec::new();

        inputs.push((
            Cow::from("inputs_embeds"),
            Value::from_array(inputs_embeds)?.into_dyn(),
        ));
        inputs.push((
            Cow::from("position_ids"),
            Value::from_array(position_ids)?.into_dyn(),
        ));
        inputs.push((
            Cow::from("attention_mask"),
            Value::from_array(attention_mask)?.into_dyn(),
        ));

        for layer_idx in 0..NUM_LAYERS {
            let key_name = format!("past_key_values.{}.key", layer_idx);
            let value_name = format!("past_key_values.{}.value", layer_idx);

            let key_tensor =
                Value::from_array(past_key_values[layer_idx * 2].clone())?.into_dyn();
            let value_tensor =
                Value::from_array(past_key_values[layer_idx * 2 + 1].clone())?.into_dyn();

            inputs.push((Cow::from(key_name), key_tensor));
            inputs.push((Cow::from(value_name), value_tensor));
        }

        let mut lm = self
            .language_model
            .lock()
            .map_err(|e| TtsError::Inference(e.to_string()))?;
        let outputs = lm.run(inputs)?;

        let logits = extract_f32_tensor(&outputs[0])?;

        let mut new_kv = Vec::with_capacity(NUM_LAYERS * 2);
        for layer_idx in 0..NUM_LAYERS {
            let key_idx = 1 + layer_idx * 2;
            let value_idx = 2 + layer_idx * 2;

            let key_arr = extract_f32_tensor(&outputs[key_idx])?;
            let value_arr = extract_f32_tensor(&outputs[value_idx])?;

            let key_4d = key_arr
                .into_dimensionality::<ndarray::Ix4>()
                .map_err(|e| TtsError::Inference(e.to_string()))?;
            let value_4d = value_arr
                .into_dimensionality::<ndarray::Ix4>()
                .map_err(|e| TtsError::Inference(e.to_string()))?;

            new_kv.push(key_4d.to_owned());
            new_kv.push(value_4d.to_owned());
        }

        Ok((logits, new_kv))
    }

    fn decode_speech_tokens(
        &self,
        speech_tokens: &[i64],
        speaker_embeddings: &ArrayD<f32>,
        speaker_features: &ArrayD<f32>,
    ) -> Result<Vec<f32>, TtsError> {
        if speech_tokens.is_empty() {
            return Ok(Vec::new());
        }

        let tokens_arr =
            Array2::from_shape_vec((1, speech_tokens.len()), speech_tokens.to_vec())
                .map_err(|e| TtsError::Inference(e.to_string()))?;

        let mut inputs: Vec<(Cow<str>, DynValue)> = Vec::new();
        inputs.push((
            Cow::from("speech_tokens"),
            Value::from_array(tokens_arr)?.into_dyn(),
        ));
        inputs.push((
            Cow::from("speaker_embeddings"),
            Value::from_array(speaker_embeddings.clone())?.into_dyn(),
        ));
        inputs.push((
            Cow::from("speaker_features"),
            Value::from_array(speaker_features.clone())?.into_dyn(),
        ));

        let mut decoder = self
            .conditional_decoder
            .lock()
            .map_err(|e| TtsError::Inference(e.to_string()))?;
        let outputs = decoder.run(inputs)?;

        let waveform = extract_f32_tensor(&outputs[0])?;

        Ok(waveform.iter().copied().collect())
    }
}

#[async_trait::async_trait]
impl TtsEngine for ChatterboxTTS {
    async fn generate(
        &self,
        text: &str,
        reference_audio: Option<&[f32]>,
        reference_sample_rate: Option<u32>,
        _cancel_flag: Option<Arc<AtomicBool>>,
    ) -> Result<Vec<AudioChunk>, TtsError> {
        let samples = match reference_audio {
            Some(audio) => {
                let sr = reference_sample_rate.unwrap_or(SAMPLE_RATE);
                self.generate_tts_with_samples(text, audio, sr)?
            }
            None => return Err(TtsError::VoiceRequired),
        };

        Ok(vec![AudioChunk {
            samples,
            sample_rate: SAMPLE_RATE,
            is_final: true,
        }])
    }

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

fn download_models(target_dir: &Path) -> Result<(), TtsError> {
    fs::create_dir_all(target_dir)?;

    let api = Api::new().map_err(|e| TtsError::ModelLoad(e.to_string()))?;
    let repo = api.model(MODEL_ID.to_string());

    let model_files = [
        "onnx/speech_encoder.onnx",
        "onnx/speech_encoder.onnx_data",
        "onnx/embed_tokens.onnx",
        "onnx/embed_tokens.onnx_data",
        "onnx/language_model.onnx",
        "onnx/language_model.onnx_data",
        "onnx/conditional_decoder.onnx",
        "onnx/conditional_decoder.onnx_data",
        "tokenizer.json",
    ];

    for file in &model_files {
        println!("Downloading {}...", file);
        let downloaded_path = repo
            .get(file)
            .map_err(|e| TtsError::ModelLoad(e.to_string()))?;

        let filename = Path::new(file).file_name().unwrap();
        let target_path = target_dir.join(filename);

        if !target_path.exists() {
            fs::copy(&downloaded_path, &target_path)?;
        }
    }

    println!("Models downloaded to {:?}", target_dir);
    Ok(())
}
