use std::{
    fs,
    path::{Path, PathBuf},
};

use anyhow::{Context, Result};
use tauri::{Emitter, Manager, Window};
use uuid::Uuid;

use crate::{
    audio::AudioPipeline,
    models::{
        DefaultModelPaths, ErrorEvent, LogEvent, OutputMode, ProgressEvent, ResetSegmentsEvent,
        StartTaskPayload, SubtitleSegment, SubtitleTask, TaskStatus, TranslationConfig,
    },
    state::AppState,
    subtitle::{render, SubtitleFormat},
    translate::Translator,
    vad::{VadConfig, VadEngine},
    whisper::WhisperEngine,
};

const DEFAULT_WHISPER_MODEL: &str = "model/ggml-small-q5_1.bin";
const DEFAULT_VAD_MODEL: &str = "model/silero_vad.onnx";
#[cfg(all(target_os = "macos", target_arch = "aarch64"))]
const DEFAULT_FFMPEG_BINARY: &str = "vendor/ffmpeg/macos-arm64/bin/ffmpeg";
#[cfg(all(target_os = "macos", target_arch = "x86_64"))]
const DEFAULT_FFMPEG_BINARY: &str = "vendor/ffmpeg/macos-x86_64/bin/ffmpeg";

pub async fn start_task(
    app: tauri::AppHandle,
    window: Window,
    state: tauri::State<'_, AppState>,
    mut payload: StartTaskPayload,
) -> Result<SubtitleTask> {
    if payload.whisper_model_path.as_deref().is_none_or(str::is_empty) {
        payload.whisper_model_path = resolve_default_model_path(&app, DEFAULT_WHISPER_MODEL);
    }
    if payload.vad_model_path.as_deref().is_none_or(str::is_empty) {
        payload.vad_model_path = resolve_default_model_path(&app, DEFAULT_VAD_MODEL);
    }
    if payload.source_lang.as_deref().is_none_or(str::is_empty) {
        payload.source_lang = Some("auto".to_string());
    }

    let file_path = PathBuf::from(&payload.file_path);
    let task = SubtitleTask {
        id: Uuid::new_v4().to_string(),
        file_name: file_path
            .file_name()
            .and_then(|item| item.to_str())
            .unwrap_or("unknown")
            .to_string(),
        file_path: payload.file_path.clone(),
        source_lang: payload.source_lang.clone(),
        target_lang: payload.target_lang.clone(),
        output_mode: payload.output_mode.clone(),
        bilingual_output: payload.bilingual_output,
        status: TaskStatus::Queued,
        progress: 0.0,
        segments: Vec::new(),
        error: None,
    };

    state.upsert_task(task.clone())?;

    let task_for_spawn = task.clone();
    let payload_for_spawn = payload.clone();
    let app_handle = app.clone();
    let app_handle_for_error = app.clone();
    let window_handle = window.clone();
    let task_id = task.id.clone();

    tauri::async_runtime::spawn(async move {
        if let Err(error) = run_pipeline(app_handle, window_handle.clone(), task_for_spawn, payload_for_spawn).await {
            if let Ok(mut failed_task) = app_handle_for_error.state::<AppState>().get_task(&task_id) {
                failed_task.status = TaskStatus::Failed;
                failed_task.error = Some(error.to_string());
                let _ = app_handle_for_error.state::<AppState>().upsert_task(failed_task);
            }
            let _ = emit_error(&window_handle, &task_id, &error.to_string());
        }
    });

    Ok(task)
}

pub fn get_default_model_paths(app: &tauri::AppHandle) -> Result<DefaultModelPaths> {
    let whisper_model_path = resolve_default_model_path(app, DEFAULT_WHISPER_MODEL)
        .ok_or_else(|| anyhow::anyhow!("未找到内置 Whisper 模型: {}", DEFAULT_WHISPER_MODEL))?;
    let vad_model_path = resolve_default_model_path(app, DEFAULT_VAD_MODEL)
        .ok_or_else(|| anyhow::anyhow!("未找到内置 VAD 模型: {}", DEFAULT_VAD_MODEL))?;

    Ok(DefaultModelPaths {
        whisper_model_path,
        vad_model_path,
    })
}

fn resolve_default_model_path(app: &tauri::AppHandle, relative_path: &str) -> Option<String> {
    if let Ok(resource_dir) = app.path().resource_dir() {
        let bundled_path = resource_dir.join(relative_path);
        if bundled_path.exists() {
            return Some(bundled_path.to_string_lossy().to_string());
        }
    }

    let local_fallback_path = Path::new(env!("CARGO_MANIFEST_DIR")).join(relative_path);
    if local_fallback_path.exists() {
        return Some(local_fallback_path.to_string_lossy().to_string());
    }

    None
}

fn resolve_ffmpeg_path(app: &tauri::AppHandle) -> Option<PathBuf> {
    if let Ok(resource_dir) = app.path().resource_dir() {
        let bundled_path = resource_dir.join(DEFAULT_FFMPEG_BINARY);
        if bundled_path.exists() {
            return Some(bundled_path);
        }
    }

    let local_bundled_path = Path::new(env!("CARGO_MANIFEST_DIR")).join(DEFAULT_FFMPEG_BINARY);
    if local_bundled_path.exists() {
        return Some(local_bundled_path);
    }

    let path_var = std::env::var_os("PATH")?;
    for directory in std::env::split_paths(&path_var) {
        let candidate = directory.join("ffmpeg");
        if candidate.exists() {
            return Some(candidate);
        }
    }

    None
}

async fn run_pipeline(
    app: tauri::AppHandle,
    window: Window,
    mut task: SubtitleTask,
    payload: StartTaskPayload,
) -> Result<()> {
    let app_state = app.state::<AppState>();
    let workspace = std::env::temp_dir().join("crosssubtitle-ai").join(&task.id);
    let should_translate = matches!(payload.output_mode, OutputMode::Translate);
    let ffmpeg_path = resolve_ffmpeg_path(&app)
        .ok_or_else(|| anyhow::anyhow!("未找到可用 ffmpeg，请重新执行打包命令或在系统中安装 ffmpeg"))?;

    set_status(&window, &app_state, &mut task, TaskStatus::Extracting, 8.0, "正在抽取音频")?;
    emit_log(&window, &task.id, format!("task: input file={}", payload.file_path))?;
    emit_log(&window, &task.id, format!("audio: ffmpeg={}", ffmpeg_path.display()))?;
    let wav_path = AudioPipeline::extract_to_wav(&ffmpeg_path, &payload.file_path, &workspace)?;
    emit_log(&window, &task.id, format!("audio: normalized wav={}", wav_path.display()))?;

    set_status(&window, &app_state, &mut task, TaskStatus::VadProcessing, 22.0, "正在分析语音片段")?;
    let samples = AudioPipeline::load_wav_f32(&wav_path)?;
    let vad = VadEngine::new(payload.vad_model_path.clone(), VadConfig::default())?;
    let speech_ranges = vad.detect_segments(&samples);
    emit_log(
        &window,
        &task.id,
        format!("vad: detected {} speech ranges", speech_ranges.len()),
    )?;

    set_status(&window, &app_state, &mut task, TaskStatus::Transcribing, 45.0, "正在执行 Whisper")?;
    let whisper = WhisperEngine::new(payload.whisper_model_path.clone());
    let task_id_for_progress = task.id.clone();
    let task_id_for_segment = task.id.clone();
    let task_id_for_reset = task.id.clone();
    let task_id_for_log = task.id.clone();
    let app_state_for_segment = app_state.clone();
    let app_state_for_reset = app_state.clone();
    let mut segments = whisper.infer_segments(
        &wav_path,
        &task.id,
        task.source_lang.as_deref(),
        &task.target_lang,
        should_translate,
        &speech_ranges,
        |ratio| {
            let progress = 45.0 + ratio.clamp(0.0, 1.0) * 27.0;
            window.emit(
                "task:progress",
                ProgressEvent {
                    task_id: task_id_for_progress.clone(),
                    status: TaskStatus::Transcribing,
                    progress,
                    message: "正在执行 Whisper".to_string(),
                },
            )?;
            Ok(())
        },
        || {
            if let Ok(mut current_task) = app_state_for_reset.get_task(&task_id_for_reset) {
                current_task.segments.clear();
                let _ = app_state_for_reset.upsert_task(current_task);
            }
            window.emit(
                "task:segments_reset",
                ResetSegmentsEvent {
                    task_id: task_id_for_reset.clone(),
                },
            )?;
            Ok(())
        },
        |segment| {
            if let Ok(mut current_task) = app_state_for_segment.get_task(&task_id_for_segment) {
                upsert_segment(&mut current_task.segments, segment.clone());
                let _ = app_state_for_segment.upsert_task(current_task);
            }
            window.emit(
                "task:segment",
                crate::models::SegmentEvent {
                    task_id: task_id_for_segment.clone(),
                    segment,
                },
            )?;
            Ok(())
        },
        |message| emit_log(&window, &task_id_for_log, message),
    )?;

    task.segments = segments.clone();
    app_state.upsert_task(task.clone())?;

    if should_translate {
        let config = payload
            .translation_config
            .clone()
            .or_else(load_translation_config)
            .ok_or_else(|| anyhow::anyhow!("翻译模式需要填写 LLM API 配置，或设置 OPENAI_API_BASE / OPENAI_API_KEY"))?;
        set_status(&window, &app_state, &mut task, TaskStatus::Translating, 72.0, "正在生成译文")?;
        let translator = Translator::new(config)?;
        let task_id_for_translate = task.id.clone();
        let app_state_for_translate = app_state.clone();
        let window_for_translate = window.clone();
        segments = translator
            .translate_segments_with_progress(
                &segments,
                &task.target_lang,
                |message| {
                    let _ = emit_log(&window_for_translate, &task_id_for_translate, message);
                },
                |segment| {
                    if let Ok(mut current_task) = app_state_for_translate.get_task(&task_id_for_translate) {
                        upsert_segment(&mut current_task.segments, segment.clone());
                        let _ = app_state_for_translate.upsert_task(current_task);
                    }
                    let _ = window_for_translate.emit(
                        "task:segment",
                        crate::models::SegmentEvent {
                            task_id: task_id_for_translate.clone(),
                            segment,
                        },
                    );
                },
            )
            .await?;
        task.segments = segments.clone();
        app_state.upsert_task(task.clone())?;

        for segment in segments {
            window.emit(
                "task:segment",
                crate::models::SegmentEvent {
                    task_id: task.id.clone(),
                    segment,
                },
            )?;
        }
    }

    task.status = TaskStatus::Completed;
    task.progress = 100.0;
    app_state.upsert_task(task.clone())?;
    window.emit("task:done", task)?;
    Ok(())
}

fn load_translation_config() -> Option<TranslationConfig> {
    let api_base = std::env::var("OPENAI_API_BASE").ok()?;
    let api_key = std::env::var("OPENAI_API_KEY").ok()?;
    let model = std::env::var("OPENAI_MODEL").unwrap_or_else(|_| "GLM-4-Flash-250414".to_string());
    Some(TranslationConfig {
        api_base,
        api_key,
        model,
        batch_size: 12,
        context_size: 3,
    })
}

fn set_status(
    window: &Window,
    state: &AppState,
    task: &mut SubtitleTask,
    status: TaskStatus,
    progress: f32,
    message: &str,
) -> Result<()> {
    task.status = status.clone();
    task.progress = progress;
    state.upsert_task(task.clone())?;
    window.emit(
        "task:progress",
        ProgressEvent {
            task_id: task.id.clone(),
            status,
            progress,
            message: message.to_string(),
        },
    )?;
    Ok(())
}

pub fn update_segment_text(state: tauri::State<'_, AppState>, segment: SubtitleSegment) -> Result<SubtitleTask> {
    state.update_segment(segment)
}

pub fn list_tasks(state: tauri::State<'_, AppState>) -> Result<Vec<SubtitleTask>> {
    state.list_tasks()
}

pub fn export_task(state: tauri::State<'_, AppState>, task_id: String, format: String) -> Result<String> {
    let task = state.get_task(&task_id)?;
    let format = SubtitleFormat::try_from(format.as_str())?;
    let content = render(&task.segments, format, task.bilingual_output);

    let source_path = PathBuf::from(&task.file_path);
    let stem = source_path
        .file_stem()
        .and_then(|item| item.to_str())
        .unwrap_or("subtitle");

    let output_dir = source_path
        .parent()
        .map(PathBuf::from)
        .unwrap_or(std::env::current_dir().context("failed to get current directory")?);
    fs::create_dir_all(&output_dir)?;

    let output_path = output_dir.join(format!("{stem}.{}", format.extension()));
    fs::write(&output_path, content)?;

    Ok(output_path.display().to_string())
}

fn emit_error(window: &Window, task_id: &str, message: &str) -> Result<()> {
    window.emit(
        "task:error",
        ErrorEvent {
            task_id: task_id.to_string(),
            message: message.to_string(),
        },
    )?;
    Ok(())
}

fn emit_log(window: &Window, task_id: &str, message: String) -> Result<()> {
    window.emit(
        "task:log",
        LogEvent {
            task_id: task_id.to_string(),
            message,
        },
    )?;
    Ok(())
}

fn upsert_segment(segments: &mut Vec<SubtitleSegment>, segment: SubtitleSegment) {
    if let Some(existing) = segments.iter_mut().find(|item| item.id == segment.id) {
        *existing = segment;
    } else {
        segments.push(segment);
    }

    segments.sort_by(|left, right| {
        left.start
            .partial_cmp(&right.start)
            .unwrap_or(std::cmp::Ordering::Equal)
            .then_with(|| left.end.partial_cmp(&right.end).unwrap_or(std::cmp::Ordering::Equal))
            .then_with(|| left.id.cmp(&right.id))
    });
}