use askama::Template;
use axum::{
    Form, Router,
    body::Body,
    extract::{Path, State},
    http::Request,
    response::{Html, Redirect},
    routing::{get, post},
};
use rusqlite::params;
use std::io::{Cursor, Read};

use crate::auth::CurrentUser;
use crate::mods;
use crate::routes::AppState;
use crate::sanitize;

#[derive(Template)]
#[template(path = "mods/list.html")]
struct ModListTemplate {
    username: String,
    is_superuser: bool,
    password_change_required: bool,
    instance_name: String,
    instance_id: i64,
    mods: Vec<ModRow>,
    flash: Option<FlashMessage>,
}

#[derive(Debug)]
struct ModRow {
    id: i64,
    filename: String,
    display_name: Option<String>,
    side: String,
    accepted: bool,
    enabled: bool,
    rejection_reason: Option<String>,
    created_at: String,
}

struct FlashMessage {
    kind: String,
    text: String,
}

/// Helper: extract all `mod_id` values from raw form key-value pairs.
fn parse_mod_ids(pairs: &[(String, String)]) -> Vec<i64> {
    pairs
        .iter()
        .filter(|(k, _)| k == "mod_id")
        .filter_map(|(_, v)| v.parse().ok())
        .collect()
}

pub fn router() -> Router<AppState> {
    Router::new()
        .route("/instances/{id}/mods", get(list_mods).post(upload_mod))
        .route("/instances/{id}/mods/{mod_id}/delete", post(delete_mod))
        .route("/instances/{id}/mods/{mod_id}/toggle", post(toggle_mod))
        .route("/instances/{id}/mods/batch-disable", post(batch_disable))
        .route("/instances/{id}/mods/batch-delete", post(batch_delete))
        .route("/instances/{id}/mods/batch-toggle", post(batch_toggle))
        .route("/instances/{id}/mods/rescan", post(rescan_mods))
}

async fn list_mods(
    State(state): State<AppState>,
    Path(instance_id): Path<i64>,
    CurrentUser(account): CurrentUser,
) -> Result<Html<String>, axum::response::Redirect> {
    let conn = state.db.conn();
    let instance_name: String = conn
        .query_row(
            "SELECT name FROM instances WHERE id = ?1",
            params![instance_id],
            |row| row.get(0),
        )
        .map_err(|_| Redirect::to("/instances"))?;

    let mut stmt = conn
        .prepare(
            "SELECT id, filename, display_name, side, accepted, enabled, rejection_reason, created_at
             FROM mods WHERE instance_id = ?1 ORDER BY created_at DESC",
        )
        .map_err(|_| Redirect::to("/instances"))?;

    let mods: Vec<ModRow> = stmt
        .query_map(params![instance_id], |row| {
            Ok(ModRow {
                id: row.get(0)?,
                filename: row.get(1)?,
                display_name: row.get(2)?,
                side: row.get(3)?,
                accepted: row.get::<_, i32>(4)? != 0,
                enabled: row.get::<_, i32>(5)? != 0,
                rejection_reason: row.get(6)?,
                created_at: row.get(7)?,
            })
        })
        .map_err(|_| Redirect::to("/instances"))?
        .filter_map(|r| r.ok())
        .collect();
    drop(stmt);
    drop(conn);

    let template = ModListTemplate {
        username: account.username.clone(),
        is_superuser: account.is_superuser,
        password_change_required: account.password_change_required,
        instance_name,
        instance_id,
        mods,
        flash: None,
    };

    match template.render() {
        Ok(html) => Ok(Html(html)),
        Err(e) => {
            tracing::error!("Failed to render mods template: {e}");
            Err(Redirect::to("/instances"))
        }
    }
}

// ── Single-mod actions ───────────────────────────────────────────────

async fn upload_mod(
    State(state): State<AppState>,
    Path(instance_id): Path<i64>,
    CurrentUser(_user): CurrentUser,
    req: Request<Body>,
) -> Result<Redirect, axum::response::Redirect> {
    tracing::info!("Upload mod request for instance {instance_id}");

    let instance_name = match get_instance_name(&state, instance_id) {
        Some(n) => n,
        None => return Err(Redirect::to("/instances")),
    };

    let safe_name = match sanitize::sanitize_instance_name(&instance_name) {
        Some(n) => n,
        None => return Err(Redirect::to("/instances")),
    };

    let mods_dir = state
        .config
        .server_directory
        .join("instances")
        .join(&safe_name)
        .join("data")
        .join("mods");
    let _ = std::fs::create_dir_all(&mods_dir);

    // Build multer multipart parser
    let (parts, body) = req.into_parts();
    let content_type = parts
        .headers
        .get("content-type")
        .and_then(|v| v.to_str().ok())
        .unwrap_or("");

    let boundary = content_type
        .split(';')
        .find_map(|part| {
            let part = part.trim();
            part.strip_prefix("boundary=").map(|b| b.trim_matches('"').to_string())
        })
        .unwrap_or_default();

    if boundary.is_empty() {
        tracing::error!("No boundary found in Content-Type");
        return Err(Redirect::to(&format!("/instances/{instance_id}/mods")));
    }

    let constraints = multer::Constraints::new()
        .size_limit(multer::SizeLimit::new()
            .whole_stream(500 * 1024 * 1024)
            .per_field(500 * 1024 * 1024));
    let stream = body.into_data_stream();
    let mut multipart = multer::Multipart::with_constraints(stream, boundary, constraints);

    let mut processed = 0u32;
    loop {
        match multipart.next_field().await {
            Ok(Some(field)) => {
                let file_name = field
                    .file_name()
                    .map(|s| s.to_string())
                    .unwrap_or_else(|| "mod.jar".to_string());
                let buf = match field.bytes().await {
                    Ok(b) => b.to_vec(),
                    Err(e) => {
                        tracing::error!("Failed to read field bytes: {e}");
                        continue;
                    }
                };
                if buf.is_empty() {
                    continue;
                }

                let lower = file_name.to_lowercase();
                if lower.ends_with(".zip") {
                    process_zip_upload(&state, instance_id, &buf, &file_name, &mods_dir);
                } else if lower.ends_with(".jar") {
                    process_jar_upload(&state, instance_id, &buf, &file_name, &mods_dir);
                }
                processed += 1;
            }
            Ok(None) => break,
            Err(e) => {
                tracing::error!("Multer error: {e}");
                break;
            }
        }
    }

    tracing::info!("Upload done, processed {processed} files");
    Ok(Redirect::to(&format!("/instances/{instance_id}/mods")))
}

/// Toggle a mod between enabled and disabled.
/// Disabled = `.jar` renamed to `.jar.disabled` on disk so the server skips it.
async fn toggle_mod(
    State(state): State<AppState>,
    Path((instance_id, mod_id)): Path<(i64, i64)>,
    CurrentUser(_user): CurrentUser,
) -> Result<Redirect, axum::response::Redirect> {
    let conn = state.db.conn();
    let (filename, instance_name, currently_enabled): (String, String, bool) = conn
        .query_row(
            "SELECT m.filename, i.name, m.enabled FROM mods m
             JOIN instances i ON i.id = m.instance_id
             WHERE m.id = ?1 AND m.instance_id = ?2",
            params![mod_id, instance_id],
            |row| Ok((row.get(0)?, row.get(1)?, row.get::<_, i32>(2)? != 0)),
        )
        .map_err(|_| Redirect::to(&format!("/instances/{instance_id}/mods")))?;
    drop(conn);

    let safe_name = sanitize::sanitize_instance_name(&instance_name)
        .ok_or_else(|| Redirect::to(&format!("/instances/{instance_id}/mods")))?;
    let safe_filename = sanitize::sanitize_backup_filename(&filename)
        .ok_or_else(|| Redirect::to(&format!("/instances/{instance_id}/mods")))?;

    let mods_dir = state
        .config
        .server_directory
        .join("instances")
        .join(&safe_name)
        .join("data")
        .join("mods");

    let base_path = mods_dir.join(&safe_filename);

    if currently_enabled {
        // Disable: rename .jar → .jar.disabled
        let disabled_path = mods_dir.join(format!("{safe_filename}.disabled"));
        if base_path.exists() {
            let _ = std::fs::rename(&base_path, &disabled_path);
        }
    } else {
        // Enable: rename .jar.disabled → .jar
        let disabled_path = mods_dir.join(format!("{safe_filename}.disabled"));
        if disabled_path.exists() {
            let _ = std::fs::rename(&disabled_path, &base_path);
        } else if !base_path.exists() {
            // Neither exists — file may have been deleted out of band; just toggle the DB
            tracing::warn!("Mod file not found on disk: {safe_filename}");
        }
    }

    let conn = state.db.conn();
    let _ = conn.execute(
        "UPDATE mods SET enabled = NOT enabled WHERE id = ?1",
        params![mod_id],
    );
    drop(conn);

    Ok(Redirect::to(&format!("/instances/{instance_id}/mods")))
}

/// Permanently delete a single mod (file + DB record).
async fn delete_mod(
    State(state): State<AppState>,
    Path((instance_id, mod_id)): Path<(i64, i64)>,
    CurrentUser(_user): CurrentUser,
) -> Result<Redirect, axum::response::Redirect> {
    let conn = state.db.conn();
    let (filename, instance_name): (String, String) = conn
        .query_row(
            "SELECT m.filename, i.name FROM mods m
             JOIN instances i ON i.id = m.instance_id
             WHERE m.id = ?1 AND m.instance_id = ?2",
            params![mod_id, instance_id],
            |row| Ok((row.get(0)?, row.get(1)?)),
        )
        .map_err(|_| Redirect::to(&format!("/instances/{instance_id}/mods")))?;

    let safe_name = sanitize::sanitize_instance_name(&instance_name)
        .ok_or_else(|| Redirect::to(&format!("/instances/{instance_id}/mods")))?;
    let safe_filename = sanitize::sanitize_backup_filename(&filename)
        .ok_or_else(|| Redirect::to(&format!("/instances/{instance_id}/mods")))?;

    let mods_dir = state
        .config
        .server_directory
        .join("instances")
        .join(&safe_name)
        .join("data")
        .join("mods");

    // Try deleting both the .jar and the .jar.disabled variant
    let jar_path = mods_dir.join(&safe_filename);
    let disabled_path = mods_dir.join(format!("{safe_filename}.disabled"));
    let _ = std::fs::remove_file(&jar_path);
    let _ = std::fs::remove_file(&disabled_path);

    // Remove from DB
    conn.execute("DELETE FROM mods WHERE id = ?1", params![mod_id])
        .ok();

    let remaining: i64 = conn
        .query_row(
            "SELECT COUNT(*) FROM mods WHERE instance_id = ?1 AND accepted = 1",
            params![instance_id],
            |row| row.get(0),
        )
        .unwrap_or(0);
    if remaining == 0 {
        conn.execute(
            "UPDATE instances SET has_modpack = 0 WHERE id = ?1",
            params![instance_id],
        )
        .ok();
    }
    drop(conn);

    Ok(Redirect::to(&format!("/instances/{instance_id}/mods")))
}

// ── Batch actions ─────────────────────────────────────────────────────

/// Disable all checked mods at once.
async fn batch_disable(
    State(state): State<AppState>,
    Path(instance_id): Path<i64>,
    CurrentUser(_user): CurrentUser,
    Form(form): Form<Vec<(String, String)>>,
) -> Result<Redirect, axum::response::Redirect> {
    let mod_ids = parse_mod_ids(&form);
    for mod_id in &mod_ids {
        let conn = state.db.conn();
        let (filename, instance_name): (String, String) = match conn.query_row(
            "SELECT m.filename, i.name FROM mods m
             JOIN instances i ON i.id = m.instance_id
             WHERE m.id = ?1 AND m.instance_id = ?2",
            params![mod_id, instance_id],
            |row| Ok((row.get(0)?, row.get(1)?)),
        ) {
            Ok(v) => v,
            Err(_) => continue,
        };
        drop(conn);

        let safe_name = match sanitize::sanitize_instance_name(&instance_name) {
            Some(n) => n,
            None => continue,
        };
        let safe_filename = match sanitize::sanitize_backup_filename(&filename) {
            Some(f) => f,
            None => continue,
        };

        let mods_dir = state
            .config
            .server_directory
            .join("instances")
            .join(&safe_name)
            .join("data")
            .join("mods");

        let jar = mods_dir.join(&safe_filename);
        let disabled = mods_dir.join(format!("{safe_filename}.disabled"));
        if jar.exists() {
            let _ = std::fs::rename(&jar, &disabled);
        }

        let conn = state.db.conn();
        let _ = conn.execute(
            "UPDATE mods SET enabled = 0 WHERE id = ?1",
            params![mod_id],
        );
        drop(conn);
    }

    Ok(Redirect::to(&format!("/instances/{instance_id}/mods")))
}

/// Permanently delete all checked mods at once.
async fn batch_delete(
    State(state): State<AppState>,
    Path(instance_id): Path<i64>,
    CurrentUser(_user): CurrentUser,
    Form(form): Form<Vec<(String, String)>>,
) -> Result<Redirect, axum::response::Redirect> {
    let mod_ids = parse_mod_ids(&form);
    for mod_id in &mod_ids {
        let conn = state.db.conn();
        let (filename, instance_name): (String, String) = match conn.query_row(
            "SELECT m.filename, i.name FROM mods m
             JOIN instances i ON i.id = m.instance_id
             WHERE m.id = ?1 AND m.instance_id = ?2",
            params![mod_id, instance_id],
            |row| Ok((row.get(0)?, row.get(1)?)),
        ) {
            Ok(v) => v,
            Err(_) => continue,
        };
        drop(conn);

        let safe_name = match sanitize::sanitize_instance_name(&instance_name) {
            Some(n) => n,
            None => continue,
        };
        let safe_filename = match sanitize::sanitize_backup_filename(&filename) {
            Some(f) => f,
            None => continue,
        };

        let mods_dir = state
            .config
            .server_directory
            .join("instances")
            .join(&safe_name)
            .join("data")
            .join("mods");

        let _ = std::fs::remove_file(mods_dir.join(&safe_filename));
        let _ = std::fs::remove_file(mods_dir.join(format!("{safe_filename}.disabled")));

        let conn = state.db.conn();
        conn.execute("DELETE FROM mods WHERE id = ?1", params![mod_id])
            .ok();
        drop(conn);
    }

    // Update has_modpack flag
    let conn = state.db.conn();
    let remaining: i64 = conn
        .query_row(
            "SELECT COUNT(*) FROM mods WHERE instance_id = ?1 AND accepted = 1",
            params![instance_id],
            |row| row.get(0),
        )
        .unwrap_or(0);
    if remaining == 0 {
        let _ = conn.execute(
            "UPDATE instances SET has_modpack = 0 WHERE id = ?1",
            params![instance_id],
        );
    }
    drop(conn);

    Ok(Redirect::to(&format!("/instances/{instance_id}/mods")))
}

/// Toggle (enable/disable) all checked mods at once — each flips its state.
async fn batch_toggle(
    State(state): State<AppState>,
    Path(instance_id): Path<i64>,
    CurrentUser(_user): CurrentUser,
    Form(form): Form<Vec<(String, String)>>,
) -> Result<Redirect, axum::response::Redirect> {
    let mod_ids = parse_mod_ids(&form);
    for mod_id in &mod_ids {
        let conn = state.db.conn();
        let (filename, instance_name, currently_enabled): (String, String, bool) =
            match conn.query_row(
                "SELECT m.filename, i.name, m.enabled FROM mods m
             JOIN instances i ON i.id = m.instance_id
             WHERE m.id = ?1 AND m.instance_id = ?2",
                params![mod_id, instance_id],
                |row| Ok((row.get(0)?, row.get(1)?, row.get::<_, i32>(2)? != 0)),
            ) {
                Ok(v) => v,
                Err(_) => continue,
            };
        drop(conn);

        let safe_name = match sanitize::sanitize_instance_name(&instance_name) {
            Some(n) => n,
            None => continue,
        };
        let safe_filename = match sanitize::sanitize_backup_filename(&filename) {
            Some(f) => f,
            None => continue,
        };

        let mods_dir = state
            .config
            .server_directory
            .join("instances")
            .join(&safe_name)
            .join("data")
            .join("mods");

        let jar = mods_dir.join(&safe_filename);
        let disabled = mods_dir.join(format!("{safe_filename}.disabled"));

        if currently_enabled {
            // Was enabled → now disable
            if jar.exists() {
                let _ = std::fs::rename(&jar, &disabled);
            }
        } else {
            // Was disabled → now enable
            if disabled.exists() {
                let _ = std::fs::rename(&disabled, &jar);
            }
        }

        let conn = state.db.conn();
        let _ = conn.execute(
            "UPDATE mods SET enabled = NOT enabled WHERE id = ?1",
            params![mod_id],
        );
        drop(conn);
    }

    Ok(Redirect::to(&format!("/instances/{instance_id}/mods")))
}

// ── Helpers ───────────────────────────────────────────────────────────

fn get_instance_name(state: &AppState, id: i64) -> Option<String> {
    let conn = state.db.conn();
    let result = conn
        .query_row(
            "SELECT name FROM instances WHERE id = ?1",
            params![id],
            |row| row.get::<_, String>(0),
        )
        .ok();
    drop(conn);
    result
}

fn process_jar_upload(
    state: &AppState,
    instance_id: i64,
    bytes: &[u8],
    filename: &str,
    mods_dir: &std::path::Path,
) {
    let safe_name = std::path::Path::new(filename)
        .file_name()
        .map(|n| n.to_string_lossy().to_string())
        .unwrap_or_else(|| filename.to_string());

    tracing::info!("Validating {safe_name}");
    let result = mods::validate_mod(bytes, &safe_name);

    let conn = state.db.conn();
    if let Err(e) = conn.execute(
        "INSERT INTO mods (instance_id, filename, display_name, side, accepted, rejection_reason, enabled)
         VALUES (?1, ?2, ?3, ?4, ?5, ?6, 1)",
        params![
            instance_id,
            safe_name,
            result.display_name,
            result.side.to_string(),
            result.accepted,
            result.rejection_reason,
        ],
    ) {
        tracing::error!("DB insert failed: {e}");
        drop(conn);
        return;
    }
    drop(conn);

    if result.accepted {
        let dest = mods_dir.join(&safe_name);
        if std::fs::write(&dest, bytes).is_ok() {
            tracing::info!("Written to disk: {}", dest.display());
        } else {
            tracing::error!("Failed to write {}", dest.display());
        }

        let conn = state.db.conn();
        let _ = conn.execute(
            "UPDATE instances SET has_modpack = 1 WHERE id = ?1",
            params![instance_id],
        );
        drop(conn);
    }
}

fn process_zip_upload(
    state: &AppState,
    instance_id: i64,
    bytes: &[u8],
    filename: &str,
    mods_dir: &std::path::Path,
) {
    tracing::info!("Extracting ZIP archive {filename}");
    let cursor = Cursor::new(bytes);
    let mut archive = match zip::ZipArchive::new(cursor) {
        Ok(a) => a,
        Err(e) => {
            tracing::error!("Failed to read ZIP {filename}: {e}");
            return;
        }
    };

    for i in 0..archive.len().min(500) {
        let mut entry = match archive.by_index(i) {
            Ok(e) => e,
            Err(_) => continue,
        };

        let entry_name = entry.name().to_string();
        let lower = entry_name.to_lowercase();
        if !lower.ends_with(".jar") {
            continue;
        }

        let base_name = std::path::Path::new(&entry_name)
            .file_name()
            .map(|n| n.to_string_lossy().to_string())
            .unwrap_or_else(|| entry_name.clone());

        let mut jar_bytes = Vec::new();
        if entry.read_to_end(&mut jar_bytes).is_err() {
            continue;
        }

        process_jar_upload(state, instance_id, &jar_bytes, &base_name, mods_dir);
    }
}

async fn rescan_mods(
    State(state): State<AppState>,
    Path(instance_id): Path<i64>,
    CurrentUser(_user): CurrentUser,
) -> Result<Redirect, axum::response::Redirect> {
    let instance_name = match get_instance_name(&state, instance_id) {
        Some(n) => n,
        None => return Err(Redirect::to("/instances")),
    };

    let safe_name = match sanitize::sanitize_instance_name(&instance_name) {
        Some(n) => n,
        None => return Err(Redirect::to("/instances")),
    };

    let mods_dir = state
        .config
        .server_directory
        .join("instances")
        .join(&safe_name)
        .join("data")
        .join("mods");

    if let Ok(entries) = std::fs::read_dir(&mods_dir) {
        for entry in entries.flatten() {
            let path = entry.path();
            if !path.is_file() {
                continue;
            }
            let filename = path
                .file_name()
                .map(|n| n.to_string_lossy().to_string())
                .unwrap_or_default();
            // Skip disabled mods (intentionally deactivated) and non-jar files
            if !filename.ends_with(".jar") || filename.ends_with(".jar.disabled") {
                continue;
            }
            let data = match std::fs::read(&path) {
                Ok(d) => d,
                Err(_) => continue,
            };

            tracing::info!("Rescanning existing mod: {filename}");
            process_jar_upload(&state, instance_id, &data, &filename, &mods_dir);
        }
    }

    Ok(Redirect::to(&format!("/instances/{instance_id}/mods")))
}