package database

import (
	"context"

	"gitea.mrixs.me/minecraft-platform/backend/internal/models"
	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgxpool"
)

type ModpackRepository struct {
	DB *pgxpool.Pool
}

// CreateModpackTx создает модпак и все его файлы в одной транзакции.
func (r *ModpackRepository) CreateModpackTx(ctx context.Context, modpack *models.Modpack, files []models.ModpackFile) error {
	tx, err := r.DB.Begin(ctx)
	if err != nil {
		return err
	}
	defer tx.Rollback(ctx)

	var modpackID int
	err = tx.QueryRow(ctx,
		"INSERT INTO modpacks (name, display_name, minecraft_version) VALUES ($1, $2, $3) RETURNING id",
		modpack.Name, modpack.DisplayName, modpack.MinecraftVersion,
	).Scan(&modpackID)
	if err != nil {
		return err
	}

	rows := make([][]interface{}, len(files))
	for i, f := range files {
		rows[i] = []interface{}{modpackID, f.RelativePath, f.FileHash, f.FileSize, f.DownloadURL}
	}

	_, err = tx.CopyFrom(
		ctx,
		pgx.Identifier{"modpack_files"},
		[]string{"modpack_id", "relative_path", "file_hash", "file_size", "download_url"},
		pgx.CopyFromRows(rows),
	)
	if err != nil {
		return err
	}

	return tx.Commit(ctx)
}

// GetModpackManifest возвращает список файлов для указанного модпака.
func (r *ModpackRepository) GetModpackManifest(ctx context.Context, modpackName string) ([]models.ManifestEntry, error) {
	query := `
		SELECT mf.relative_path, mf.file_hash, mf.file_size
		FROM modpack_files mf
		JOIN modpacks m ON mf.modpack_id = m.id
		WHERE m.name = $1 AND m.is_active = TRUE`

	rows, err := r.DB.Query(ctx, query, modpackName)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var manifest []models.ManifestEntry
	for rows.Next() {
		var entry models.ManifestEntry
		if err := rows.Scan(&entry.Path, &entry.Hash, &entry.Size); err != nil {
			return nil, err
		}
		manifest = append(manifest, entry)
	}

	if len(manifest) == 0 {
		var exists bool
		err := r.DB.QueryRow(ctx, "SELECT EXISTS(SELECT 1 FROM modpacks WHERE name = $1)", modpackName).Scan(&exists)
		if err != nil || !exists {
			return nil, pgx.ErrNoRows
		}
	}

	return manifest, nil
}

// GetAllFileHashes извлекает все уникальные хеши файлов из базы данных.
func (r *ModpackRepository) GetAllFileHashes(ctx context.Context) (map[string]struct{}, error) {
	query := "SELECT DISTINCT file_hash FROM modpack_files"
	rows, err := r.DB.Query(ctx, query)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	hashes := make(map[string]struct{})
	for rows.Next() {
		var hash string
		if err := rows.Scan(&hash); err != nil {
			return nil, err
		}
		hashes[hash] = struct{}{}
	}

	return hashes, rows.Err()
}

// GetModpacksSummary возвращает список всех активных модпаков с датой последнего обновления.
func (r *ModpackRepository) GetModpacksSummary(ctx context.Context) ([]models.ModpackSummary, error) {
	query := `
		SELECT name, updated_at
		FROM modpacks
		WHERE is_active = TRUE`

	rows, err := r.DB.Query(ctx, query)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var summaries []models.ModpackSummary
	for rows.Next() {
		var s models.ModpackSummary
		if err := rows.Scan(&s.Name, &s.UpdatedAt); err != nil {
			return nil, err
		}
		summaries = append(summaries, s)
	}

	return summaries, nil
}