use anyhow::Result;
use futures::stream::{self, StreamExt};
use image::GenericImageView;
use parsers::{analyze_book, BookFormat};
use sqlx::Row;
use std::path::Path;
use std::sync::atomic::{AtomicBool, AtomicI32, Ordering};
use std::sync::Arc;
use tracing::{info, warn};
use uuid::Uuid;

use crate::{job::is_job_cancelled, utils, AppState};

#[derive(Clone)]
struct ThumbnailConfig {
    enabled: bool,
    width: u32,
    height: u32,
    quality: u8,
    directory: String,
}

async fn load_thumbnail_config(pool: &sqlx::PgPool) -> ThumbnailConfig {
    let fallback = ThumbnailConfig {
        enabled: true,
        width: 300,
        height: 400,
        quality: 80,
        directory: "/data/thumbnails".to_string(),
    };
    let row = sqlx::query(r#"SELECT value FROM app_settings WHERE key = 'thumbnail'"#)
        .fetch_optional(pool)
        .await;

    match row {
        Ok(Some(row)) => {
            let value: serde_json::Value = row.get("value");
            ThumbnailConfig {
                enabled: value
                    .get("enabled")
                    .and_then(|v| v.as_bool())
                    .unwrap_or(fallback.enabled),
                width: value
                    .get("width")
                    .and_then(|v| v.as_u64())
                    .map(|v| v as u32)
                    .unwrap_or(fallback.width),
                height: value
                    .get("height")
                    .and_then(|v| v.as_u64())
                    .map(|v| v as u32)
                    .unwrap_or(fallback.height),
                quality: value
                    .get("quality")
                    .and_then(|v| v.as_u64())
                    .map(|v| v as u8)
                    .unwrap_or(fallback.quality),
                directory: value
                    .get("directory")
                    .and_then(|v| v.as_str())
                    .map(|s| s.to_string())
                    .unwrap_or_else(|| fallback.directory.clone()),
            }
        }
        _ => fallback,
    }
}

async fn load_thumbnail_concurrency(pool: &sqlx::PgPool) -> usize {
    let default_concurrency = 2;
    let row = sqlx::query(r#"SELECT value FROM app_settings WHERE key = 'limits'"#)
        .fetch_optional(pool)
        .await;

    match row {
        Ok(Some(row)) => {
            let value: serde_json::Value = row.get("value");
            value
                .get("concurrent_renders")
                .and_then(|v| v.as_u64())
                .map(|v| v as usize)
                .unwrap_or(default_concurrency)
        }
        _ => default_concurrency,
    }
}

fn generate_thumbnail(image_bytes: &[u8], config: &ThumbnailConfig) -> anyhow::Result<Vec<u8>> {
    let img = image::load_from_memory(image_bytes)
        .map_err(|e| anyhow::anyhow!("failed to load image: {}", e))?;
    let (orig_w, orig_h) = img.dimensions();
    let ratio_w = config.width as f32 / orig_w as f32;
    let ratio_h = config.height as f32 / orig_h as f32;
    let ratio = ratio_w.min(ratio_h);
    let new_w = (orig_w as f32 * ratio) as u32;
    let new_h = (orig_h as f32 * ratio) as u32;
    let resized = img.resize(new_w, new_h, image::imageops::FilterType::Triangle);
    let rgba = resized.to_rgba8();
    let (w, h) = rgba.dimensions();
    let rgb_data: Vec<u8> = rgba.pixels().flat_map(|p| [p[0], p[1], p[2]]).collect();
    let quality = config.quality as f32;
    let webp_data = webp::Encoder::new(&rgb_data, webp::PixelLayout::Rgb, w, h).encode(quality);
    Ok(webp_data.to_vec())
}

/// Save raw image bytes (as extracted from the archive) without any processing.
fn save_raw_image(book_id: Uuid, raw_bytes: &[u8], directory: &str) -> anyhow::Result<String> {
    let dir = Path::new(directory);
    std::fs::create_dir_all(dir)?;
    let path = dir.join(format!("{}.raw", book_id));
    std::fs::write(&path, raw_bytes)?;
    Ok(path.to_string_lossy().to_string())
}

/// Resize the raw image and save it as a WebP thumbnail, overwriting the raw file.
fn resize_raw_to_webp(
    book_id: Uuid,
    raw_path: &str,
    config: &ThumbnailConfig,
) -> anyhow::Result<String> {
    let raw_bytes = std::fs::read(raw_path)
        .map_err(|e| anyhow::anyhow!("failed to read raw image {}: {}", raw_path, e))?;
    let webp_bytes = generate_thumbnail(&raw_bytes, config)?;

    let webp_path = Path::new(&config.directory).join(format!("{}.webp", book_id));
    std::fs::write(&webp_path, &webp_bytes)?;

    // Delete the raw file now that the WebP is written
    let _ = std::fs::remove_file(raw_path);

    Ok(webp_path.to_string_lossy().to_string())
}

fn book_format_from_str(s: &str) -> Option<BookFormat> {
    match s {
        "cbz" => Some(BookFormat::Cbz),
        "cbr" => Some(BookFormat::Cbr),
        "pdf" => Some(BookFormat::Pdf),
        _ => None,
    }
}

/// Phase 2 — Two-sub-phase analysis:
///
/// **Sub-phase A (extracting_pages)**: open each archive once, extract (page_count, raw_image_bytes),
/// save the raw bytes to `{directory}/{book_id}.raw`. I/O bound — runs at `concurrent_renders`.
///
/// **Sub-phase B (generating_thumbnails)**: load each `.raw` file, resize and encode as WebP,
/// overwrite as `{directory}/{book_id}.webp`. CPU bound — runs at `concurrent_renders`.
///
/// `thumbnail_only` = true: only process books missing thumbnail (page_count may already be set).
/// `thumbnail_only` = false: process books missing page_count.
pub async fn analyze_library_books(
    state: &AppState,
    job_id: Uuid,
    library_id: Option<Uuid>,
    thumbnail_only: bool,
) -> Result<()> {
    let config = load_thumbnail_config(&state.pool).await;

    if !config.enabled {
        info!("[ANALYZER] Thumbnails disabled, skipping analysis phase");
        return Ok(());
    }

    let concurrency = load_thumbnail_concurrency(&state.pool).await;

    let query_filter = if thumbnail_only {
        "b.thumbnail_path IS NULL"
    } else {
        "b.page_count IS NULL"
    };

    let sql = format!(
        r#"
        SELECT b.id AS book_id, bf.abs_path, bf.format
        FROM books b
        JOIN book_files bf ON bf.book_id = b.id
        WHERE (b.library_id = $1 OR $1 IS NULL)
          AND {}
        "#,
        query_filter
    );

    let rows = sqlx::query(&sql)
        .bind(library_id)
        .fetch_all(&state.pool)
        .await?;

    if rows.is_empty() {
        info!("[ANALYZER] No books to analyze");
        return Ok(());
    }

    let total = rows.len() as i32;
    info!(
        "[ANALYZER] Analyzing {} books (thumbnail_only={}, concurrency={})",
        total, thumbnail_only, concurrency
    );

    let cancelled_flag = Arc::new(AtomicBool::new(false));
    let cancel_pool = state.pool.clone();
    let cancel_flag_for_poller = cancelled_flag.clone();
    let cancel_handle = tokio::spawn(async move {
        loop {
            tokio::time::sleep(tokio::time::Duration::from_secs(2)).await;
            match is_job_cancelled(&cancel_pool, job_id).await {
                Ok(true) => {
                    cancel_flag_for_poller.store(true, Ordering::Relaxed);
                    break;
                }
                Ok(false) => {}
                Err(_) => break,
            }
        }
    });

    struct BookTask {
        book_id: Uuid,
        abs_path: String,
        format: String,
    }

    let tasks: Vec<BookTask> = rows
        .into_iter()
        .map(|row| BookTask {
            book_id: row.get("book_id"),
            abs_path: row.get("abs_path"),
            format: row.get("format"),
        })
        .collect();

    // -------------------------------------------------------------------------
    // Sub-phase A: extract first page from each archive and store raw image
    // I/O bound — limited by HDD throughput, runs at `concurrency`
    // -------------------------------------------------------------------------
    let phase_a_start = std::time::Instant::now();
    let _ = sqlx::query(
        "UPDATE index_jobs SET status = 'extracting_pages', total_files = $2, processed_files = 0, current_file = NULL WHERE id = $1",
    )
    .bind(job_id)
    .bind(total)
    .execute(&state.pool)
    .await;

    let extracted_count = Arc::new(AtomicI32::new(0));

    // Collected results: (book_id, raw_path, page_count)
    let extracted: Vec<(Uuid, String, i32)> = stream::iter(tasks)
        .map(|task| {
            let pool = state.pool.clone();
            let config = config.clone();
            let cancelled = cancelled_flag.clone();
            let extracted_count = extracted_count.clone();

            async move {
                if cancelled.load(Ordering::Relaxed) {
                    return None;
                }

                let local_path = utils::remap_libraries_path(&task.abs_path);
                let path = std::path::Path::new(&local_path);
                let book_id = task.book_id;

                let format = match book_format_from_str(&task.format) {
                    Some(f) => f,
                    None => {
                        warn!("[ANALYZER] Unknown format '{}' for book {}", task.format, book_id);
                        return None;
                    }
                };

                let pdf_scale = config.width.max(config.height);
                let path_owned = path.to_path_buf();
                let analyze_result =
                    tokio::task::spawn_blocking(move || analyze_book(&path_owned, format, pdf_scale))
                        .await;

                let (page_count, raw_bytes) = match analyze_result {
                    Ok(Ok(result)) => result,
                    Ok(Err(e)) => {
                        warn!("[ANALYZER] analyze_book failed for book {}: {}", book_id, e);
                        let _ = sqlx::query(
                            "UPDATE book_files SET parse_status = 'error', parse_error_opt = $2 WHERE book_id = $1",
                        )
                        .bind(book_id)
                        .bind(e.to_string())
                        .execute(&pool)
                        .await;
                        return None;
                    }
                    Err(e) => {
                        warn!("[ANALYZER] spawn_blocking error for book {}: {}", book_id, e);
                        return None;
                    }
                };

                // Save raw bytes to disk (no resize, no encode)
                let raw_path = match tokio::task::spawn_blocking({
                    let dir = config.directory.clone();
                    let bytes = raw_bytes.clone();
                    move || save_raw_image(book_id, &bytes, &dir)
                })
                .await
                {
                    Ok(Ok(p)) => p,
                    Ok(Err(e)) => {
                        warn!("[ANALYZER] save_raw_image failed for book {}: {}", book_id, e);
                        return None;
                    }
                    Err(e) => {
                        warn!("[ANALYZER] spawn_blocking save_raw error for book {}: {}", book_id, e);
                        return None;
                    }
                };

                // Update page_count in DB
                if let Err(e) = sqlx::query("UPDATE books SET page_count = $1 WHERE id = $2")
                    .bind(page_count)
                    .bind(book_id)
                    .execute(&pool)
                    .await
                {
                    warn!("[ANALYZER] DB page_count update failed for book {}: {}", book_id, e);
                    return None;
                }

                let processed = extracted_count.fetch_add(1, Ordering::Relaxed) + 1;
                let percent = (processed as f64 / total as f64 * 50.0) as i32; // first 50%
                let _ = sqlx::query(
                    "UPDATE index_jobs SET processed_files = $2, progress_percent = $3 WHERE id = $1",
                )
                .bind(job_id)
                .bind(processed)
                .bind(percent)
                .execute(&pool)
                .await;

                Some((book_id, raw_path, page_count))
            }
        })
        .buffer_unordered(concurrency)
        .filter_map(|x| async move { x })
        .collect()
        .await;

    if cancelled_flag.load(Ordering::Relaxed) {
        cancel_handle.abort();
        info!("[ANALYZER] Job {} cancelled during extraction phase", job_id);
        return Err(anyhow::anyhow!("Job cancelled by user"));
    }

    let extracted_total = extracted.len() as i32;
    let phase_a_elapsed = phase_a_start.elapsed();
    info!(
        "[ANALYZER] Sub-phase A complete: {}/{} books extracted in {:.1}s ({:.0} ms/book)",
        extracted_total,
        total,
        phase_a_elapsed.as_secs_f64(),
        if extracted_total > 0 { phase_a_elapsed.as_millis() as f64 / extracted_total as f64 } else { 0.0 }
    );

    // -------------------------------------------------------------------------
    // Sub-phase B: resize raw images and encode as WebP
    // CPU bound — can run at higher concurrency than I/O phase
    // -------------------------------------------------------------------------
    let phase_b_start = std::time::Instant::now();
    let _ = sqlx::query(
        "UPDATE index_jobs SET status = 'generating_thumbnails', generating_thumbnails_started_at = NOW(), total_files = $2, processed_files = 0, current_file = NULL WHERE id = $1",
    )
    .bind(job_id)
    .bind(extracted_total)
    .execute(&state.pool)
    .await;

    let resize_count = Arc::new(AtomicI32::new(0));

    stream::iter(extracted)
        .for_each_concurrent(concurrency, |(book_id, raw_path, page_count)| {
            let pool = state.pool.clone();
            let config = config.clone();
            let cancelled = cancelled_flag.clone();
            let resize_count = resize_count.clone();

            async move {
                if cancelled.load(Ordering::Relaxed) {
                    return;
                }

                let raw_path_clone = raw_path.clone();
                let thumb_result = tokio::task::spawn_blocking(move || {
                    resize_raw_to_webp(book_id, &raw_path_clone, &config)
                })
                .await;

                let thumb_path = match thumb_result {
                    Ok(Ok(p)) => p,
                    Ok(Err(e)) => {
                        warn!("[ANALYZER] resize_raw_to_webp failed for book {}: {}", book_id, e);
                        // page_count is already set; thumbnail stays NULL
                        return;
                    }
                    Err(e) => {
                        warn!("[ANALYZER] spawn_blocking resize error for book {}: {}", book_id, e);
                        return;
                    }
                };

                if let Err(e) = sqlx::query(
                    "UPDATE books SET page_count = $1, thumbnail_path = $2 WHERE id = $3",
                )
                .bind(page_count)
                .bind(&thumb_path)
                .bind(book_id)
                .execute(&pool)
                .await
                {
                    warn!("[ANALYZER] DB thumbnail update failed for book {}: {}", book_id, e);
                    return;
                }

                let processed = resize_count.fetch_add(1, Ordering::Relaxed) + 1;
                let percent =
                    50 + (processed as f64 / extracted_total as f64 * 50.0) as i32; // last 50%
                let _ = sqlx::query(
                    "UPDATE index_jobs SET processed_files = $2, progress_percent = $3 WHERE id = $1",
                )
                .bind(job_id)
                .bind(processed)
                .bind(percent)
                .execute(&pool)
                .await;
            }
        })
        .await;

    cancel_handle.abort();

    if cancelled_flag.load(Ordering::Relaxed) {
        info!("[ANALYZER] Job {} cancelled during resize phase", job_id);
        return Err(anyhow::anyhow!("Job cancelled by user"));
    }

    let final_count = resize_count.load(Ordering::Relaxed);
    let phase_b_elapsed = phase_b_start.elapsed();
    info!(
        "[ANALYZER] Sub-phase B complete: {}/{} thumbnails generated in {:.1}s ({:.0} ms/book)",
        final_count,
        extracted_total,
        phase_b_elapsed.as_secs_f64(),
        if final_count > 0 { phase_b_elapsed.as_millis() as f64 / final_count as f64 } else { 0.0 }
    );
    info!(
        "[ANALYZER] Total: {:.1}s (extraction {:.1}s + resize {:.1}s)",
        (phase_a_elapsed + phase_b_elapsed).as_secs_f64(),
        phase_a_elapsed.as_secs_f64(),
        phase_b_elapsed.as_secs_f64(),
    );

    Ok(())
}

/// Clear thumbnail files and DB references for books in scope, then re-analyze.
pub async fn regenerate_thumbnails(
    state: &AppState,
    job_id: Uuid,
    library_id: Option<Uuid>,
) -> Result<()> {
    let config = load_thumbnail_config(&state.pool).await;

    let book_ids_to_clear: Vec<Uuid> = sqlx::query_scalar(
        r#"SELECT id FROM books WHERE (library_id = $1 OR $1 IS NULL) AND thumbnail_path IS NOT NULL"#,
    )
    .bind(library_id)
    .fetch_all(&state.pool)
    .await
    .unwrap_or_default();

    let mut deleted_count = 0usize;
    for book_id in &book_ids_to_clear {
        // Delete WebP thumbnail
        let webp_path = Path::new(&config.directory).join(format!("{}.webp", book_id));
        if webp_path.exists() {
            if let Err(e) = std::fs::remove_file(&webp_path) {
                warn!("[ANALYZER] Failed to delete thumbnail {}: {}", webp_path.display(), e);
            } else {
                deleted_count += 1;
            }
        }
        // Delete raw file if it exists (interrupted previous run)
        let raw_path = Path::new(&config.directory).join(format!("{}.raw", book_id));
        let _ = std::fs::remove_file(&raw_path);
    }
    info!("[ANALYZER] Deleted {} thumbnail files for regeneration", deleted_count);

    sqlx::query(r#"UPDATE books SET thumbnail_path = NULL WHERE (library_id = $1 OR $1 IS NULL)"#)
        .bind(library_id)
        .execute(&state.pool)
        .await?;

    analyze_library_books(state, job_id, library_id, true).await
}

/// Delete orphaned thumbnail files (books deleted in full_rebuild get new UUIDs).
pub async fn cleanup_orphaned_thumbnails(state: &AppState) -> Result<()> {
    let config = load_thumbnail_config(&state.pool).await;

    let existing_book_ids: std::collections::HashSet<Uuid> =
        sqlx::query_scalar(r#"SELECT id FROM books"#)
            .fetch_all(&state.pool)
            .await
            .unwrap_or_default()
            .into_iter()
            .collect();

    let thumbnail_dir = Path::new(&config.directory);
    if !thumbnail_dir.exists() {
        return Ok(());
    }

    let mut deleted_count = 0usize;
    if let Ok(entries) = std::fs::read_dir(thumbnail_dir) {
        for entry in entries.flatten() {
            let file_name = entry.file_name();
            let file_name = file_name.to_string_lossy();
            // Clean up both .webp and orphaned .raw files
            let stem = if let Some(s) = file_name.strip_suffix(".webp") {
                Some(s.to_string())
            } else if let Some(s) = file_name.strip_suffix(".raw") {
                Some(s.to_string())
            } else {
                None
            };
            if let Some(book_id_str) = stem {
                if let Ok(book_id) = Uuid::parse_str(&book_id_str) {
                    if !existing_book_ids.contains(&book_id) {
                        if let Err(e) = std::fs::remove_file(entry.path()) {
                            warn!("Failed to delete orphaned file {}: {}", entry.path().display(), e);
                        } else {
                            deleted_count += 1;
                        }
                    }
                }
            }
        }
    }

    info!("[ANALYZER] Deleted {} orphaned thumbnail files", deleted_count);
    Ok(())
}