package store

import (
	"context"
	"fmt"
	"io/fs"
	"sort"
	"strings"

	"github.com/jackc/pgx/v5/pgxpool"

	"github.com/hhs/camtalk/internal/logger"
)

// RunMigrations 从给定的 fs.FS 中读取 *.up.sql 文件并按版本号顺序执行。
// 已执行过的版本会跳过（通过 schema_migrations 表记录）。
func RunMigrations(ctx context.Context, pool *pgxpool.Pool, fsys fs.FS) error {
	// 确保 schema_migrations 表存在
	if _, err := pool.Exec(ctx, `CREATE TABLE IF NOT EXISTS schema_migrations (
		version INTEGER PRIMARY KEY,
		applied_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
	)`); err != nil {
		return fmt.Errorf("create schema_migrations table: %w", err)
	}

	// 收集所有 *.up.sql 文件
	entries, err := fs.ReadDir(fsys, ".")
	if err != nil {
		return fmt.Errorf("read migrations dir: %w", err)
	}

	var files []string
	for _, e := range entries {
		if !e.IsDir() && strings.HasSuffix(e.Name(), ".up.sql") {
			files = append(files, e.Name())
		}
	}
	sort.Strings(files)

	for _, name := range files {
		// 从文件名提取版本号，如 "001_users.up.sql" → 1
		var version int
		if _, err := fmt.Sscanf(name, "%d_", &version); err != nil {
			return fmt.Errorf("parse version from %s: %w", name, err)
		}

		// 检查是否已执行
		var exists bool
		if err := pool.QueryRow(ctx,
			`SELECT EXISTS(SELECT 1 FROM schema_migrations WHERE version = $1)`, version,
		).Scan(&exists); err != nil {
			return fmt.Errorf("check migration version %d: %w", version, err)
		}
		if exists {
			logger.Log.Debugw("migration already applied", "version", version, "file", name)
			continue
		}

		// 读取并执行
		content, err := fs.ReadFile(fsys, name)
		if err != nil {
			return fmt.Errorf("read migration %s: %w", name, err)
		}

		if _, err := pool.Exec(ctx, string(content)); err != nil {
			return fmt.Errorf("execute migration %s: %w", name, err)
		}

		// 记录已执行
		if _, err := pool.Exec(ctx,
			`INSERT INTO schema_migrations (version) VALUES ($1)`, version,
		); err != nil {
			return fmt.Errorf("record migration %d: %w", version, err)
		}

		logger.Log.Infow("migration applied", "version", version, "file", name)
	}

	return nil
}