package database

import (
	"context"
	"database/sql"
	"encoding/json"
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"strings"

	"entgo.io/ent/dialect"
	entsql "entgo.io/ent/dialect/sql"
	"home-vue-go/internal/config"
	"home-vue-go/internal/ent"
	"home-vue-go/internal/ent/migrate"

	_ "github.com/mattn/go-sqlite3"
	"golang.org/x/crypto/bcrypt"
)

const siteConfigPayloadColumn = "config_json"

type Database struct {
	Client *ent.Client
	SQL    *sql.DB
}

func Init(dbPath string, cfg *config.Config) (*Database, error) {
	db, err := sql.Open("sqlite3", dbPath+"?_fk=1")
	if err != nil {
		return nil, err
	}

	drv := entsql.OpenDB(dialect.SQLite, db)
	client := ent.NewClient(ent.Driver(drv))
	ctx := context.Background()
	if err := client.Schema.Create(ctx, migrate.WithForeignKeys(false)); err != nil {
		_ = db.Close()
		return nil, fmt.Errorf("数据库迁移失败: %w", err)
	}
	if err := ensureSiteConfigPayload(db); err != nil {
		_ = client.Close()
		_ = db.Close()
		return nil, err
	}

	database := &Database{Client: client, SQL: db}
	if err := initDefaultData(ctx, client); err != nil {
		_ = database.Close()
		return nil, fmt.Errorf("初始化默认数据失败: %w", err)
	}
	if err := initializeSiteSettings(ctx, database, cfg); err != nil {
		_ = database.Close()
		return nil, fmt.Errorf("初始化站点配置载荷失败: %w", err)
	}
	return database, nil
}

func (d *Database) Close() error {
	if d.Client != nil {
		return d.Client.Close()
	}
	if d.SQL != nil {
		return d.SQL.Close()
	}
	return nil
}

func ensureSiteConfigPayload(db *sql.DB) error {
	rows, err := db.Query("PRAGMA table_info(site_configs)")
	if err != nil {
		return err
	}
	defer rows.Close()
	for rows.Next() {
		var cid int
		var name, columnType string
		var notNull, primaryKey int
		var defaultValue any
		if err := rows.Scan(&cid, &name, &columnType, &notNull, &defaultValue, &primaryKey); err != nil {
			return err
		}
		if name == siteConfigPayloadColumn {
			return rows.Err()
		}
	}
	if err := rows.Err(); err != nil {
		return err
	}
	_, err = db.Exec(`ALTER TABLE site_configs ADD COLUMN config_json TEXT NOT NULL DEFAULT '{}'`)
	return err
}

func initDefaultData(ctx context.Context, client *ent.Client) error {
	if _, err := client.SiteConfig.Get(ctx, 1); err != nil {
		if !ent.IsNotFound(err) {
			return err
		}
		if _, err := client.SiteConfig.Create().
			SetSiteName("个人主页").
			SetSiteURL("https://example.com").
			SetSiteIcon("/favicon.ico").
			SetSiteDescription("一个基于Vue3的个人主页").
			SetSiteKeywords("个人主页,Vue3").
			SetUserName("用户").
			SetProfileImageURL("").
			SetIcpNumber("").
			SetPoliceNumber("").
			SetPageTitle("个人主页").
			SetFavicon("/favicon.ico").
			SetUmamiScript("").
			SetUmamiWebsiteID("").
			SetIconLibrary("").
			SetFontLibrary("").
			Save(ctx); err != nil {
			return err
		}
	}

	userCount, err := client.User.Query().Count(ctx)
	if err != nil {
		return err
	}
	if userCount == 0 {
		hashedPassword, err := bcrypt.GenerateFromPassword([]byte("admin123"), bcrypt.DefaultCost)
		if err != nil {
			return err
		}
		_, err = client.User.Create().
			SetUsername("admin").
			SetPassword(string(hashedPassword)).
			Save(ctx)
		return err
	}
	return nil
}

func initializeSiteSettings(ctx context.Context, db *Database, cfg *config.Config) error {
	payload, err := db.loadSiteConfigPayload(ctx)
	if err != nil {
		return err
	}
	if strings.TrimSpace(payload) != "" && strings.TrimSpace(payload) != "{}" {
		var settings config.SiteSettings
		if err := json.Unmarshal([]byte(payload), &settings); err != nil {
			return fmt.Errorf("解析站点配置载荷失败: %w", err)
		}
		return nil
	}

	siteCfg, err := db.Client.SiteConfig.Get(ctx, 1)
	if err != nil {
		return err
	}
	settings := config.DefaultSiteSettings()
	settings.SiteName = siteCfg.SiteName
	settings.SiteURL = siteCfg.SiteURL
	settings.SiteIcon = siteCfg.SiteIcon
	settings.SiteDescription = siteCfg.SiteDescription
	settings.SiteKeywords = siteCfg.SiteKeywords
	settings.UserName = siteCfg.UserName
	settings.ProfileImageURL = siteCfg.ProfileImageURL
	settings.ICPNumber = siteCfg.IcpNumber
	settings.PoliceNumber = siteCfg.PoliceNumber
	settings.PageTitle = siteCfg.PageTitle
	settings.Favicon = siteCfg.Favicon
	settings.IconLibrary = siteCfg.IconLibrary
	settings.FontLibrary = siteCfg.FontLibrary
	settings.UmamiScript = siteCfg.UmamiScript
	settings.UmamiWebsiteID = siteCfg.UmamiWebsiteID

	if cfg != nil {
		if err := importLegacyJSON(cfg.DataDir, settings); err != nil {
			return err
		}
	}
	settings.Normalize()
	return db.SaveSiteSettings(ctx, settings)
}

func importLegacyJSON(dataDir string, settings *config.SiteSettings) error {
	if dataDir == "" {
		return nil
	}
	var footer struct {
		Start string `json:"start"`
		End   string `json:"end"`
	}
	if err := readOptionalJSON(filepath.Join(dataDir, "footer_year.json"), &footer); err != nil {
		return err
	}
	if footer.Start != "" || footer.End != "" {
		settings.FooterYearStart, settings.FooterYearEnd = footer.Start, footer.End
	}

	var timer config.VisitTimerConfig
	if err := readOptionalJSON(filepath.Join(dataDir, "visit_timer.json"), &timer); err != nil {
		return err
	}
	if _, err := os.Stat(filepath.Join(dataDir, "visit_timer.json")); err == nil {
		settings.ShowVisitTimer = timer.ShowVisitTimer
	}

	var texts config.RotatingTextsConfig
	if err := readOptionalJSON(filepath.Join(dataDir, "rotating_texts.json"), &texts); err != nil {
		return err
	}
	if len(texts.Texts) > 0 {
		settings.RotatingTexts = texts.Texts
	}
	return nil
}

func readOptionalJSON(path string, target any) error {
	data, err := os.ReadFile(path)
	if os.IsNotExist(err) {
		return nil
	}
	if err != nil {
		return err
	}
	if err := json.Unmarshal(data, target); err != nil {
		return fmt.Errorf("解析 %s 失败: %w", filepath.Base(path), err)
	}
	return nil
}

func (d *Database) loadSiteConfigPayload(ctx context.Context) (string, error) {
	var payload string
	err := d.SQL.QueryRowContext(ctx, "SELECT config_json FROM site_configs WHERE id = 1").Scan(&payload)
	if errors.Is(err, sql.ErrNoRows) {
		return "", nil
	}
	return payload, err
}

func (d *Database) LoadSiteSettings(ctx context.Context) (*config.SiteSettings, error) {
	payload, err := d.loadSiteConfigPayload(ctx)
	if err != nil {
		return nil, err
	}
	settings := config.DefaultSiteSettings()
	if strings.TrimSpace(payload) != "" && strings.TrimSpace(payload) != "{}" {
		if err := json.Unmarshal([]byte(payload), settings); err != nil {
			return nil, err
		}
	}
	settings.Normalize()
	return settings, nil
}

func (d *Database) SaveSiteSettings(ctx context.Context, settings *config.SiteSettings) error {
	if settings == nil {
		return errors.New("site settings cannot be nil")
	}
	settings.Normalize()
	payload, err := json.Marshal(settings)
	if err != nil {
		return err
	}
	result, err := d.SQL.ExecContext(ctx, "UPDATE site_configs SET config_json = ? WHERE id = 1", string(payload))
	if err != nil {
		return err
	}
	if affected, err := result.RowsAffected(); err != nil {
		return err
	} else if affected != 1 {
		return errors.New("site config row does not exist")
	}
	return nil
}