use crate::models::{CookieSource, VideoMetadata};
use crate::services::{download_manager, subtitle_downloader, video_resolver};
use serde::Serialize;
use std::io::{BufRead, BufReader};
use tauri::ipc::Channel;

#[tauri::command]
pub async fn resolve_url(
    url: String,
    cookie_source: CookieSource,
) -> Result<VideoMetadata, String> {
    tokio::task::spawn_blocking(move || video_resolver::resolve(&url, &cookie_source))
        .await
        .map_err(|e| format!("Task failed: {e}"))?
}

#[derive(Clone, Serialize)]
#[serde(rename_all = "camelCase", tag = "event", content = "data")]
pub enum DownloadEvent {
    Progress { percent: f64 },
    FilePath { path: String },
    Finished { success: bool, path: String },
    Error { message: String },
}

fn variant_dir(variant: &str) -> String {
    std::env::temp_dir()
        .join("video-clipper")
        .join(variant)
        .to_string_lossy()
        .to_string()
}

#[tauri::command]
pub async fn start_download(
    url: String,
    cookie_source: CookieSource,
    format_spec: String,
    variant: String,
    on_event: Channel<DownloadEvent>,
) -> Result<(), String> {
    tokio::task::spawn_blocking(move || {
        let output_dir = variant_dir(&variant);
        std::fs::create_dir_all(&output_dir)
            .map_err(|e| format!("Failed to create dir: {e}"))?;

        eprintln!(
            "[video-clipper:download:{}] starting — format='{}' dir='{}'",
            variant, format_spec, output_dir
        );

        let (mut child, _template) =
            download_manager::start_download(&url, &cookie_source, &output_dir, &format_spec)?;

        let Some(stdout) = child.stdout.take() else {
            let status = child
                .wait()
                .map_err(|e| format!("Download failed: {e}"))?;
            let _ = on_event.send(DownloadEvent::Finished {
                success: status.success(),
                path: String::new(),
            });
            return Ok(());
        };

        let reader = BufReader::new(stdout);
        let mut last_file_path: Option<String> = None;

        for line in reader.lines().map_while(Result::ok) {
            if let Some(pct) = download_manager::parse_progress_line(&line) {
                let _ = on_event.send(DownloadEvent::Progress { percent: pct });
            }

            if line.contains("[download] Destination:") {
                if let Some(path) = line.split(": ").nth(1) {
                    let trimmed = path.trim().trim_matches('"').to_string();
                    let _ = on_event.send(DownloadEvent::FilePath {
                        path: trimmed.clone(),
                    });
                    last_file_path = Some(trimmed);
                }
            } else if line.contains("[Merger] Merging formats into") {
                let trimmed = line
                    .trim_start_matches("[Merger] Merging formats into ")
                    .trim()
                    .trim_matches('"')
                    .to_string();
                if !trimmed.is_empty() {
                    let _ = on_event.send(DownloadEvent::FilePath {
                        path: trimmed.clone(),
                    });
                    last_file_path = Some(trimmed);
                }
            } else if line.contains("has already been downloaded") {
                if let Some(rest) = line.strip_prefix("[download] ") {
                    if let Some(path) = rest.strip_suffix(" has already been downloaded") {
                        let trimmed = path.trim().to_string();
                        if !trimmed.is_empty() {
                            let _ = on_event.send(DownloadEvent::FilePath {
                                path: trimmed.clone(),
                            });
                            last_file_path = Some(trimmed);
                        }
                    }
                }
            }
        }

        let status = child
            .wait()
            .map_err(|e| format!("Download failed: {e}"))?;
        let path = last_file_path.unwrap_or_default();
        eprintln!(
            "[video-clipper:download:{}] finished — success={}, path='{}'",
            variant,
            status.success(),
            path
        );
        let _ = on_event.send(DownloadEvent::Finished {
            success: status.success(),
            path,
        });

        Ok(())
    })
    .await
    .map_err(|e| format!("Task failed: {e}"))?
}

/// Check if a video with the given title exists in the variant's download dir.
#[tauri::command]
pub async fn check_cached_download(title: String, variant: String) -> Option<String> {
    let dir = variant_dir(&variant);
    let dir_path = std::path::Path::new(&dir);
    if !dir_path.is_dir() {
        return None;
    }
    let entries = std::fs::read_dir(dir_path).ok()?;
    for entry in entries.flatten() {
        let path = entry.path();
        if path.is_file() {
            if let Some(stem) = path.file_stem().and_then(|s| s.to_str()) {
                if stem == title {
                    let path_str = path.to_string_lossy().to_string();
                    if let Ok(meta) = std::fs::metadata(&path_str) {
                        if meta.len() > 0 {
                            eprintln!(
                                "[video-clipper:cache:{}] found: '{}'",
                                variant, path_str
                            );
                            return Some(path_str);
                        }
                    }
                }
            }
        }
    }
    None
}

/// Download English VTT subtitles for a video URL.
/// Returns the path to the .vtt file, or an error string.
#[tauri::command]
pub async fn download_subtitles(
    url: String,
    cookie_source: CookieSource,
    is_auto: bool,
) -> Result<String, String> {
    tokio::task::spawn_blocking(move || {
        let output_dir = std::env::temp_dir()
            .join("video-clipper")
            .join("subtitles")
            .to_string_lossy()
            .to_string();

        eprintln!(
            "[video-clipper:subtitles] downloading (auto={}) to '{}'",
            is_auto, output_dir
        );

        let result =
            subtitle_downloader::download_subtitles(&url, &cookie_source, &output_dir, is_auto);

        match &result {
            Ok(path) => eprintln!("[video-clipper:subtitles] done: '{}'", path),
            Err(e) => eprintln!("[video-clipper:subtitles] FAILED: {}", e),
        }
        result
    })
    .await
    .map_err(|e| format!("Task failed: {e}"))?
}