package dbx

import (
	"context"
	"database/sql"
	"errors"
	"fmt"
	"reflect"
	"slices"
	"strings"

	"gitea.auvem.com/go-toolkit/app"
	"github.com/fatih/color"
	"github.com/go-jet/jet/v2/mysql"
	"github.com/go-jet/jet/v2/qrm"
	_ "github.com/go-sql-driver/mysql"
)

// ModuleDBName is the name of the database module.
const ModuleDBName = "database"

var (
	// ErrNoRows is returned when a query returns no rows.
	ErrNoRows = qrm.ErrNoRows

	// SQLDB stores the current SQL database handle.
	SQLDB *sql.DB

	// config stores the database connection configuration.
	config DBConfig

	// dbModule is the singleton module instance for the database connection.
	dbModule *app.Module
)

// ModuleDB returns the database module with the provided configuration.
func ModuleDB(cfg DBConfig, forceDebugLog bool) *app.Module {
	if dbModule != nil {
		panic("ModuleDB initialized multiple times")
	}

	config = cfg // store configuration at package level

	if forceDebugLog {
		config.DebugLog = true // force debug logging if requested
	}

	dbModule = app.NewModule(ModuleDBName, app.ModuleOpts{
		Setup:    setupDB,
		Teardown: teardownDB,
	})

	return dbModule
}

// setupDB connects to the MySQL DB and initializes the goose migration provider.
// If auto migrations are enabled in configuration, latest migrations are applied.
func setupDB() error {
	if SQLDB != nil && SQLDB.Ping() == nil {
		dbModule.Logger().Warn("Database connection already established")
		return nil
	}

	var err error
	db_path := fmt.Sprintf("%s:%s@tcp(%s)/%s?charset=utf8mb4&parseTime=True&loc=Local",
		config.User, config.Password, config.Path, config.Name)

	SQLDB, err = sql.Open("mysql", db_path)
	if err != nil {
		dbModule.Logger().Error("Couldn't open SQL database", "user", config.User, "name", config.Name, "err", err)
		return err
	}

	if err := SQLDB.Ping(); err != nil {
		dbModule.Logger().Error("Couldn't ping SQL database", "user", config.User, "name", config.Name, "err", err)
		return err
	}

	SQLDB.SetMaxOpenConns(config.MaxConn)

	stats := SQLDB.Stats()
	dbModule.Logger().Info(
		"Connected to SQL database",
		"user", config.User,
		"name", config.Name,
		"path", config.Path,
		"maxConnections", stats.MaxOpenConnections,
		"currConnections", stats.OpenConnections,
	)

	if config.DebugLog {
		initDBLogger()
	}

	return nil
}

// teardownDB closes the database connection.
func teardownDB() {
	if SQLDB == nil {
		return
	}

	if err := SQLDB.Close(); err != nil {
		dbModule.Logger().Error("Couldn't close database", "err", err)
	}
	dbModule.Logger().Info("Closed database connection")
}

// Queryable interface is an SQL driver object that can execute SQL statements
// for Jet.
type Queryable interface {
	qrm.Queryable
	Query(string, ...any) (*sql.Rows, error)
}

// Executable interface is an SQL driver object that can execute SQL statements
// for Jet.
type Executable interface {
	qrm.Executable
	Exec(string, ...any) (sql.Result, error)
}

// ExecutableTx interface is an SQL driver object that implements the Executable
// interface and can also begin a transaction.
type ExecutableTx interface {
	Executable
	Begin() (*sql.Tx, error)
}

// MustQuery executes a query and returns an error if any. Filters errors for
// db.ErrNoRows (qrm.ErrNoRows) and returns nil or the error provided in that case.
func MustQuery(sqlo Queryable, stmt mysql.Statement, dest any, notFoundErr error) error {
	err := stmt.Query(sqlo, dest)
	if err != nil {
		if errors.Is(err, qrm.ErrNoRows) {
			return notFoundErr
		}
		return err
	}
	return nil
}

// MustInsert requires at least one row to be affected by a query and returns the inserted ID
func MustInsert(sqlo Executable, stmt mysql.InsertStatement) (uint64, error) {
	res, err := stmt.Exec(sqlo)
	if err != nil {
		return 0, err
	}

	id, err := res.LastInsertId()
	if err != nil {
		return 0, err
	}

	if id < 0 {
		return 0, fmt.Errorf("MustInsert got invalid ID: %d", id)
	}

	return uint64(id), nil
}

// MustUpdate requires at least one row to be affected by a query
func MustUpdate(sqlo Executable, stmt mysql.Statement, notFoundErr error) error {
	res, err := stmt.Exec(sqlo)
	if err != nil {
		return err
	}

	rows, err := res.RowsAffected()
	if err != nil {
		return err
	}

	if rows == 0 {
		return notFoundErr
	}

	return nil
}

// MightUpdateMany expects multiple rows to be affected by a query and returns this number of rows
func MightUpdateMany(sqlo Executable, stmt mysql.Statement) (int, error) {
	res, err := stmt.Exec(sqlo)
	if err != nil {
		return 0, err
	}

	rows, err := res.RowsAffected()
	return int(rows), err
}

// SoftDelete sets the deleted_at column to the current time
func SoftDelete(sqlo Executable, tbl mysql.Table, conds mysql.BoolExpression) (int64, error) {
	stmt := tbl.UPDATE().WHERE(conds)
	query := stmt.DebugSql()

	lines := strings.Split(query, "\n")
	for i, line := range lines {
		fmt.Println(i, line)
	}

	lines = slices.Insert(lines, 2, "SET deleted_at = NOW()")
	query = strings.Join(lines, "\n")

	res, err := sqlo.Exec(query)
	if err != nil {
		return 0, err
	}

	return res.RowsAffected()
}

// NormalCols processes a list of columns and strips out any that implement any of
// mysql.ColumnTimestamp, mysql.ColumnTime, or mysql.ColumnDate
func NormalCols(cols ...mysql.Column) mysql.ColumnList {
	res := make(mysql.ColumnList, 0)

	for _, col := range cols {
		_, ok := col.(mysql.ColumnTimestamp)

		if !ok {
			_, ok = col.(mysql.ColumnTime)
		}
		if !ok {
			_, ok = col.(mysql.ColumnDate)
		}

		if !ok {
			res = append(res, col)
		}
	}

	return res
}

// ContainsCol checks if a column list contains a specific column.
func ContainsCol(cols mysql.ColumnList, col mysql.Column) bool {
	return slices.Contains(cols, col)
}

// DestName returns the name of the type passed as `destTypeStruct` as a string,
// normalized for compatibility with the Jet QRM.
func DestName(destTypeStruct interface{}, path ...string) string {
	v := reflect.ValueOf(destTypeStruct)
	for v.Kind() == reflect.Ptr {
		v = v.Elem()
	}

	destIdent := v.Type().String()
	destIdent = destIdent[strings.LastIndex(destIdent, ".")+1:]

	for i, p := range path {
		if v.Kind() != reflect.Struct {
			dbModule.Logger().Error("DestName: path parent is not a struct", "path", destIdent+"."+strings.Join(path[:i+1], "."))
			return ""
		}

		v = v.FieldByName(p)

		if !v.IsValid() {
			dbModule.Logger().Error("DestName: field does not exist", "path", destIdent+"."+strings.Join(path[:i+1], "."))
			return ""
		}

		destIdent += "." + p
	}

	return destIdent
}

// StringToFilter processes a string to be used as a filter in an SQL LIKE
// statement. It replaces all spaces with % and adds % to the beginning and
// end of the string.
func StringToFilter(str string) string {
	// Remove any existing leading or trailing % characters
	str = strings.Trim(str, "%")

	// Replace all spaces with % and add % to the beginning and end of the string
	str = strings.ReplaceAll(str, " ", "%")
	str = "%" + str + "%"

	return str
}

// initDBLogger initializes the database statement logger
func initDBLogger() {
	mysql.SetQueryLogger(func(ctx context.Context, queryInfo mysql.QueryInfo) {
		_, args := queryInfo.Statement.Sql()
		dbModule.Logger().Debug(
			"Executed SQL query",
			"args", args,
			"duration", queryInfo.Duration,
			"rows", queryInfo.RowsProcessed,
			"err", queryInfo.Err,
		)

		lines := strings.Split(queryInfo.Statement.DebugSql(), "\n")
		for i, line := range lines {
			fmt.Printf("%s\t%s\n", color.CyanString(fmt.Sprintf("%03d", i)), line)
		}
	})
}