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

use anyhow::{Context, Result};
use async_zip::tokio::write::ZipFileWriter;
use async_zip::{Compression, ZipEntryBuilder};
use chrono::{DateTime, Utc};
use futures::io::{copy as fcopy, AllowStdIo};
use include_dir::{include_dir, Dir};
use serde::Serialize;
use sqlx::PgPool;
use tokio::sync::broadcast;
use tokio_util::compat::TokioAsyncReadCompatExt;
use uuid::Uuid;

use crate::state::SseEvent;

// ── Embedded viewer assets (pre-built SvelteKit static output) ──────────────

static VIEWER_DIR: Dir<'_> = include_dir!("$CARGO_MANIFEST_DIR/static/export-viewer");

// ── DB query rows ────────────────────────────────────────────────────────────

#[derive(sqlx::FromRow)]
struct ExportUploadRow {
    id: Uuid,
    original_path: String,
    mime_type: String,
    caption: Option<String>,
    uploader_name: String,
    like_count: i64,
    created_at: DateTime<Utc>,
}

#[derive(sqlx::FromRow)]
struct ExportCommentRow {
    upload_id: Uuid,
    uploader_name: String,
    body: String,
    created_at: DateTime<Utc>,
}

// ── Viewer JSON structs (serialised to data.json) ───────────────────────────

#[derive(Serialize)]
struct ViewerData {
    event: ViewerEvent,
    posts: Vec<ViewerPost>,
}

#[derive(Serialize)]
struct ViewerEvent {
    name: String,
    exported_at: String,
}

#[derive(Serialize)]
struct ViewerPost {
    id: String,
    uploader: String,
    caption: String,
    tags: Vec<String>,
    timestamp: String,
    likes: i64,
    comments: Vec<ViewerComment>,
    media: ViewerMedia,
}

#[derive(Serialize)]
struct ViewerComment {
    author: String,
    text: String,
    timestamp: String,
}

#[derive(Serialize)]
struct ViewerMedia {
    #[serde(rename = "type")]
    media_type: String,
    thumb: String,
    full: String,
}

// ── Entry point ──────────────────────────────────────────────────────────────

pub fn spawn_export_jobs(
    event_id: Uuid,
    event_name: String,
    pool: PgPool,
    media_path: PathBuf,
    sse_tx: broadcast::Sender<SseEvent>,
) {
    let pool2 = pool.clone();
    let media_path2 = media_path.clone();
    let sse_tx2 = sse_tx.clone();
    let event_name2 = event_name.clone();

    tokio::spawn(async move {
        if let Err(e) = run_zip_export(event_id, &pool, &media_path, &sse_tx).await {
            tracing::error!("ZIP export failed for event {event_id}: {e:#}");
            mark_failed(&pool, event_id, "zip", &e.to_string()).await;
        }
        maybe_broadcast_complete(&pool, event_id, &sse_tx).await;
    });

    tokio::spawn(async move {
        if let Err(e) =
            run_html_export(event_id, &event_name2, &pool2, &media_path2, &sse_tx2).await
        {
            tracing::error!("HTML export failed for event {event_id}: {e:#}");
            mark_failed(&pool2, event_id, "html", &e.to_string()).await;
        }
        maybe_broadcast_complete(&pool2, event_id, &sse_tx2).await;
    });
}

// ── ZIP export ───────────────────────────────────────────────────────────────

async fn run_zip_export(
    event_id: Uuid,
    pool: &PgPool,
    media_path: &Path,
    sse_tx: &broadcast::Sender<SseEvent>,
) -> Result<()> {
    mark_running(pool, event_id, "zip").await;

    let uploads = query_uploads(pool, event_id).await?;
    let total = uploads.len().max(1) as f32;

    let exports_dir = media_path.join("exports");
    tokio::fs::create_dir_all(&exports_dir).await?;

    let tmp_path = exports_dir.join("Gallery.zip.tmp");
    let out_path = exports_dir.join("Gallery.zip");

    {
        let file = tokio::fs::File::create(&tmp_path).await?;
        let mut zip = ZipFileWriter::with_tokio(file);

        for (i, row) in uploads.iter().enumerate() {
            let src = media_path.join(&row.original_path);
            if !src.exists() {
                continue;
            }
            let ext = ext_from_path(&row.original_path);
            let date = row.created_at.format("%Y-%m-%d_%H-%M").to_string();
            let name_safe = sanitize_name(&row.uploader_name);
            let folder = if row.mime_type.starts_with("video/") { "Videos" } else { "Photos" };
            let entry_name = format!("{folder}/{date}_{name_safe}_{}.{ext}", row.id);

            let builder = ZipEntryBuilder::new(entry_name.into(), Compression::Stored);
            let mut entry = zip.write_entry_stream(builder).await?;

            let mut f = tokio::fs::File::open(&src).await?.compat();
            fcopy(&mut f, &mut entry).await?;
            entry.close().await?;

            let pct = ((i + 1) as f32 / total * 100.0) as i16;
            update_progress(pool, event_id, "zip", pct.min(99)).await;
        }

        zip.close().await?;
    }

    tokio::fs::rename(&tmp_path, &out_path).await?;

    sqlx::query(
        "UPDATE export_job SET status = 'done', progress_pct = 100, file_path = $2, completed_at = NOW()
         WHERE event_id = $1 AND type = 'zip'::export_type",
    )
    .bind(event_id)
    .bind("exports/Gallery.zip")
    .execute(pool)
    .await?;

    sqlx::query("UPDATE event SET export_zip_ready = TRUE WHERE id = $1")
        .bind(event_id)
        .execute(pool)
        .await?;

    let _ = sse_tx.send(SseEvent {
        event_type: "export-progress".to_string(),
        data: serde_json::json!({ "type": "zip", "progress_pct": 100 }).to_string(),
    });

    tracing::info!("ZIP export complete for event {event_id}");
    Ok(())
}

// ── HTML viewer export ──────────────────────────────────────────────────────

async fn run_html_export(
    event_id: Uuid,
    event_name: &str,
    pool: &PgPool,
    media_path: &Path,
    sse_tx: &broadcast::Sender<SseEvent>,
) -> Result<()> {
    mark_running(pool, event_id, "html").await;

    // 1. Query data
    let uploads = query_uploads(pool, event_id).await?;
    let comments = query_comments(pool, event_id).await?;
    let hashtags_per_upload = query_hashtags(pool, event_id).await?;
    let total = uploads.len().max(1) as f32;

    update_progress(pool, event_id, "html", 5).await;

    let exports_dir = media_path.join("exports");
    tokio::fs::create_dir_all(&exports_dir).await?;

    // 2. Create temp directory for media processing
    let tmp_dir = exports_dir.join(format!("viewer_tmp_{event_id}"));
    let media_tmp = tmp_dir.join("media");
    tokio::fs::create_dir_all(&media_tmp).await?;

    // 3. Process media and build post data
    let mut viewer_posts: Vec<ViewerPost> = Vec::new();

    for (i, row) in uploads.iter().enumerate() {
        let src = media_path.join(&row.original_path);
        if !src.exists() {
            continue;
        }

        let is_video = row.mime_type.starts_with("video/");
        let id_str = row.id.to_string();

        // Generate thumbnail and full variant
        let (thumb_name, full_name) = if is_video {
            let thumb = format!("{id_str}_thumb.jpg");
            let full_ext = ext_from_path(&row.original_path);
            let full = format!("{id_str}.{full_ext}");

            // Video thumbnail via ffmpeg
            let thumb_path = media_tmp.join(&thumb);
            let ffmpeg_result = tokio::process::Command::new("ffmpeg")
                .args([
                    "-i",
                    src.to_str().unwrap_or_default(),
                    "-vframes",
                    "1",
                    "-ss",
                    "00:00:01",
                    "-vf",
                    "scale=400:-1",
                    "-y",
                    thumb_path.to_str().unwrap_or_default(),
                ])
                .output()
                .await;

            match ffmpeg_result {
                Ok(output) if output.status.success() => {}
                _ => {
                    tracing::warn!("ffmpeg thumbnail failed for upload {}, skipping thumb", row.id);
                    // Create empty thumb entry — viewer handles missing thumbs gracefully
                }
            }

            // Copy video as-is
            tokio::fs::copy(&src, media_tmp.join(&full)).await?;

            (thumb, full)
        } else {
            let thumb = format!("{id_str}_thumb.jpg");
            let ext = ext_from_path(&row.original_path);
            let full = format!("{id_str}_full.{ext}");

            // Image thumbnail: resize to 400px wide
            let src_clone = src.clone();
            let thumb_path = media_tmp.join(&thumb);
            let thumb_path_clone = thumb_path.clone();

            let thumb_result = tokio::task::spawn_blocking(move || -> Result<()> {
                let img = image::open(&src_clone).context("failed to open image for thumbnail")?;
                let resized = img.resize(400, 400, image::imageops::FilterType::Lanczos3);
                resized
                    .save_with_format(&thumb_path_clone, image::ImageFormat::Jpeg)
                    .context("failed to save thumbnail")?;
                Ok(())
            })
            .await?;

            if let Err(e) = thumb_result {
                tracing::warn!("thumbnail generation failed for upload {}: {e:#}", row.id);
            }

            // Full variant: compress if >5MB, otherwise copy original
            let src_meta = tokio::fs::metadata(&src).await?;
            let full_path = media_tmp.join(&full);

            if src_meta.len() > 5_000_000 {
                // Resize to max 2000px
                let src_clone = src.clone();
                let full_path_clone = full_path.clone();

                let compress_result = tokio::task::spawn_blocking(move || -> Result<()> {
                    let img =
                        image::open(&src_clone).context("failed to open image for compression")?;
                    let resized = img.resize(2000, 2000, image::imageops::FilterType::Lanczos3);
                    resized
                        .save_with_format(&full_path_clone, image::ImageFormat::Jpeg)
                        .context("failed to save compressed full image")?;
                    Ok(())
                })
                .await?;

                if let Err(e) = compress_result {
                    tracing::warn!("compression failed for upload {}, copying original: {e:#}", row.id);
                    tokio::fs::copy(&src, &full_path).await?;
                }
            } else {
                tokio::fs::copy(&src, &full_path).await?;
            }

            (thumb, full)
        };

        // Build comments for this upload
        let post_comments: Vec<ViewerComment> = comments
            .iter()
            .filter(|c| c.upload_id == row.id)
            .map(|c| ViewerComment {
                author: c.uploader_name.clone(),
                text: c.body.clone(),
                timestamp: c.created_at.to_rfc3339(),
            })
            .collect();

        // Build tags for this upload
        let tags: Vec<String> = hashtags_per_upload
            .iter()
            .filter(|(uid, _)| *uid == row.id)
            .map(|(_, tag)| tag.clone())
            .collect();

        viewer_posts.push(ViewerPost {
            id: id_str,
            uploader: row.uploader_name.clone(),
            caption: row.caption.clone().unwrap_or_default(),
            tags,
            timestamp: row.created_at.to_rfc3339(),
            likes: row.like_count,
            comments: post_comments,
            media: ViewerMedia {
                media_type: if is_video {
                    "video".to_string()
                } else {
                    "image".to_string()
                },
                thumb: format!("media/{thumb_name}"),
                full: format!("media/{full_name}"),
            },
        });

        let pct = 10 + ((i + 1) as f32 / total * 60.0) as i16;
        update_progress(pool, event_id, "html", pct.min(69)).await;
    }

    // 4. Build data.json
    let viewer_data = ViewerData {
        event: ViewerEvent {
            name: event_name.to_string(),
            exported_at: Utc::now().to_rfc3339(),
        },
        posts: viewer_posts,
    };
    let data_json =
        serde_json::to_string_pretty(&viewer_data).context("failed to serialize data.json")?;

    update_progress(pool, event_id, "html", 72).await;

    // 5. Create ZIP
    let tmp_path = exports_dir.join("Memories.zip.tmp");
    let out_path = exports_dir.join("Memories.zip");

    {
        let file = tokio::fs::File::create(&tmp_path).await?;
        let mut zip = ZipFileWriter::with_tokio(file);

        // Write embedded viewer assets (index.html, _app/*, etc.)
        write_dir_to_zip(&VIEWER_DIR, &mut zip).await?;

        update_progress(pool, event_id, "html", 75).await;

        // Write data.json
        {
            let builder = ZipEntryBuilder::new("data.json".into(), Compression::Deflate);
            let mut entry = zip.write_entry_stream(builder).await?;
            let mut cursor = AllowStdIo::new(std::io::Cursor::new(data_json.as_bytes()));
            fcopy(&mut cursor, &mut entry).await?;
            entry.close().await?;
        }

        // Write README.txt
        {
            let builder = ZipEntryBuilder::new("README.txt".into(), Compression::Deflate);
            let mut entry = zip.write_entry_stream(builder).await?;
            let mut cursor = AllowStdIo::new(std::io::Cursor::new(README_TEXT.as_bytes()));
            fcopy(&mut cursor, &mut entry).await?;
            entry.close().await?;
        }

        update_progress(pool, event_id, "html", 78).await;

        // Write media files from temp directory
        let mut media_entries = tokio::fs::read_dir(&media_tmp).await?;
        let mut file_count = 0u32;
        let mut files_written = 0u32;

        // Count files first
        {
            let mut counter = tokio::fs::read_dir(&media_tmp).await?;
            while counter.next_entry().await?.is_some() {
                file_count += 1;
            }
        }
        let file_total = file_count.max(1) as f32;

        while let Some(dir_entry) = media_entries.next_entry().await? {
            let filename = dir_entry.file_name();
            let entry_name = format!("media/{}", filename.to_string_lossy());

            let builder = ZipEntryBuilder::new(entry_name.into(), Compression::Stored);
            let mut zip_entry = zip.write_entry_stream(builder).await?;
            let mut f = tokio::fs::File::open(dir_entry.path()).await?.compat();
            fcopy(&mut f, &mut zip_entry).await?;
            zip_entry.close().await?;

            files_written += 1;
            let pct = 78 + (files_written as f32 / file_total * 20.0) as i16;
            update_progress(pool, event_id, "html", pct.min(98)).await;
        }

        zip.close().await?;
    }

    // 6. Finalise
    tokio::fs::rename(&tmp_path, &out_path).await?;

    // Clean up temp directory
    let _ = tokio::fs::remove_dir_all(&tmp_dir).await;

    sqlx::query(
        "UPDATE export_job SET status = 'done', progress_pct = 100, file_path = $2, completed_at = NOW()
         WHERE event_id = $1 AND type = 'html'::export_type",
    )
    .bind(event_id)
    .bind("exports/Memories.zip")
    .execute(pool)
    .await?;

    sqlx::query("UPDATE event SET export_html_ready = TRUE WHERE id = $1")
        .bind(event_id)
        .execute(pool)
        .await?;

    let _ = sse_tx.send(SseEvent {
        event_type: "export-progress".to_string(),
        data: serde_json::json!({ "type": "html", "progress_pct": 100 }).to_string(),
    });

    tracing::info!("HTML viewer export complete for event {event_id}");
    Ok(())
}

// ── DB helpers ───────────────────────────────────────────────────────────────

async fn query_uploads(pool: &PgPool, event_id: Uuid) -> Result<Vec<ExportUploadRow>> {
    Ok(sqlx::query_as::<_, ExportUploadRow>(
        "SELECT u.id, u.original_path, u.mime_type, u.caption,
                usr.display_name AS uploader_name,
                COUNT(DISTINCT l.user_id) AS like_count,
                u.created_at
         FROM upload u
         JOIN \"user\" usr ON usr.id = u.user_id
         LEFT JOIN \"like\" l ON l.upload_id = u.id
         WHERE u.event_id = $1 AND u.deleted_at IS NULL AND usr.uploads_hidden = FALSE
         GROUP BY u.id, usr.display_name
         ORDER BY u.created_at ASC",
    )
    .bind(event_id)
    .fetch_all(pool)
    .await?)
}

async fn query_comments(pool: &PgPool, event_id: Uuid) -> Result<Vec<ExportCommentRow>> {
    Ok(sqlx::query_as::<_, ExportCommentRow>(
        "SELECT c.upload_id, usr.display_name AS uploader_name, c.body, c.created_at
         FROM comment c
         JOIN \"user\" usr ON usr.id = c.user_id
         JOIN upload u ON u.id = c.upload_id
         WHERE u.event_id = $1 AND c.deleted_at IS NULL AND u.deleted_at IS NULL
         ORDER BY c.created_at ASC",
    )
    .bind(event_id)
    .fetch_all(pool)
    .await?)
}

async fn query_hashtags(pool: &PgPool, event_id: Uuid) -> Result<Vec<(Uuid, String)>> {
    let rows: Vec<(Uuid, String)> = sqlx::query_as(
        "SELECT uh.upload_id, h.tag
         FROM upload_hashtag uh
         JOIN hashtag h ON h.id = uh.hashtag_id
         JOIN upload u ON u.id = uh.upload_id
         WHERE h.event_id = $1 AND u.deleted_at IS NULL",
    )
    .bind(event_id)
    .fetch_all(pool)
    .await?;
    Ok(rows)
}

async fn mark_running(pool: &PgPool, event_id: Uuid, export_type: &str) {
    let _ = sqlx::query(
        "UPDATE export_job SET status = 'running' WHERE event_id = $1 AND type = $2::export_type",
    )
    .bind(event_id)
    .bind(export_type)
    .execute(pool)
    .await;
}

async fn mark_failed(pool: &PgPool, event_id: Uuid, export_type: &str, msg: &str) {
    let _ = sqlx::query(
        "UPDATE export_job SET status = 'failed', error_message = $3
         WHERE event_id = $1 AND type = $2::export_type",
    )
    .bind(event_id)
    .bind(export_type)
    .bind(msg)
    .execute(pool)
    .await;
}

async fn update_progress(pool: &PgPool, event_id: Uuid, export_type: &str, pct: i16) {
    let _ = sqlx::query(
        "UPDATE export_job SET progress_pct = $3 WHERE event_id = $1 AND type = $2::export_type",
    )
    .bind(event_id)
    .bind(export_type)
    .bind(pct)
    .execute(pool)
    .await;
}

async fn maybe_broadcast_complete(
    pool: &PgPool,
    event_id: Uuid,
    sse_tx: &broadcast::Sender<SseEvent>,
) {
    let row: Option<(bool, bool)> = sqlx::query_as(
        "SELECT export_zip_ready, export_html_ready FROM event WHERE id = $1",
    )
    .bind(event_id)
    .fetch_optional(pool)
    .await
    .unwrap_or(None);

    if let Some((zip_ready, html_ready)) = row {
        if zip_ready && html_ready {
            let _ = sse_tx.send(SseEvent {
                event_type: "export-available".to_string(),
                data: serde_json::json!({ "types": ["zip", "html"] }).to_string(),
            });
        }
    }
}

/// Recursively write all files from an embedded `include_dir::Dir` into a ZIP.
async fn write_dir_to_zip(
    dir: &include_dir::Dir<'_>,
    zip: &mut ZipFileWriter<tokio::fs::File>,
) -> Result<()> {
    for file in dir.files() {
        let path = file.path().to_string_lossy().to_string();
        let contents = file.contents();
        let builder = ZipEntryBuilder::new(path.into(), Compression::Deflate);
        let mut entry = zip.write_entry_stream(builder).await?;
        let mut cursor = AllowStdIo::new(std::io::Cursor::new(contents));
        fcopy(&mut cursor, &mut entry).await?;
        entry.close().await?;
    }
    for sub_dir in dir.dirs() {
        Box::pin(write_dir_to_zip(sub_dir, zip)).await?;
    }
    Ok(())
}

fn ext_from_path(path: &str) -> &str {
    path.rsplit('.').next().unwrap_or("bin")
}

fn sanitize_name(name: &str) -> String {
    name.chars()
        .map(|c| if c.is_alphanumeric() || c == '-' { c } else { '_' })
        .collect()
}

// ── Static content ───────────────────────────────────────────────────────────

const README_TEXT: &str = "EventSnap Offline-Galerie\n\
\n\
So geht's:\n\
1. Entpacke diese ZIP-Datei\n\
   (Windows: Rechtsklick > \"Alle extrahieren\"; Mac: Doppelklick;\n\
    Handy: Dateimanager-App verwenden).\n\
2. Öffne \"index.html\" im Browser\n\
   (z. B. Chrome, Safari oder Firefox).\n\
3. Stöbere durch alle Fotos und Videos.\n\
   Du kannst zwischen Listen- und Rasteransicht wechseln,\n\
   nach Hashtags filtern und nach Nutzern suchen.\n\
4. Eine Internetverbindung ist nicht nötig.\n\
   Alles ist lokal auf deinem Gerät gespeichert.\n\
\n\
Viel Freude mit den Erinnerungen!\n";