package mysql

import (
	"strings"

	"git.fsdpf.net/go/db/v2"
	"git.fsdpf.net/go/db/v2/dialect/mysql"
	"git.fsdpf.net/go/db/v2/internal/sb"
	"git.fsdpf.net/go/db/v2/schema"
	"git.fsdpf.net/go/db/v2/sqlgen"
)

type Mysql struct {
	db  *db.Database
	esg sqlgen.ExpressionSQLGenerator
}

var mysqlDefaultModifiers = []string{
	"Unsigned", "Charset", "Collate", "VirtualAs", "StoredAs",
	"Nullable", "Default", "Increment", "Comment", "After", "First",
}
var mysqlSerials = []string{
	"bigInteger", "integer", "mediumInteger", "smallInteger", "tinyInteger",
}

func (this Mysql) GetColumnListing(table string) ([]string, error) {
	cols := []string{}

	err := this.db.From(db.S("information_schema").Table("columns")).Where(
		db.C("table_name").Eq(table),
		db.C("table_schema").Eq(db.L("database()")),
	).Pluck(&cols, "column_name")

	return cols, err
}

func (this Mysql) TableExists(table string) (bool, error) {
	result, err := this.db.From(db.S("information_schema").Table("tables")).Where(db.Ex{
		"table_name":   table,
		"table_type":   "BASE TABLE",
		"table_schema": db.L("database()"),
	}).Count()

	return result > 0, err
}

// 创建表
func (this Mysql) CompileCreate(bp *schema.Blueprint) []string {
	temporary := db.L("CREATE")
	if bp.IsTemporary() {
		temporary = db.L("CREATE TEMPORARY")
	}
	columns := strings.Join(this.getAddedColumns(bp), ",\n")

	sql := this.GenerateSQL("? TABLE ? (\n?\n)", temporary, db.T(bp.GetTable()), db.L(columns))

	charset := bp.GetCharset()
	if charset == "" {
		charset = "utf8mb4"
	}

	collation := bp.GetCollation()
	if collation == "" {
		collation = "utf8mb4_general_ci"
	}

	sql += this.GenerateSQL(" default charset=? collate=?", charset, collation)

	if engine := bp.GetEngine(); engine != "" {
		sql += this.GenerateSQL(" engine=?", engine)
	}

	return []string{sql}
}

// 添加字段
func (this Mysql) CompileAdd(bp *schema.Blueprint) []string {
	columns := strings.Join(schema.PrefixArray("ADD COLUMN", this.getAddedColumns(bp)), ",\n")
	sql := this.GenerateSQL("ALTER TABLE ?\n?", db.T(bp.GetTable()), db.L(columns))
	return []string{sql}
}

// 修改字段
func (this Mysql) CompileChange(bp *schema.Blueprint) []string {
	columns := strings.Join(schema.PrefixArray("CHANGE COLUMN", this.getChangedColumns(bp)), ",\n")
	sql := this.GenerateSQL("ALTER TABLE ?\n?", db.T(bp.GetTable()), db.L(columns))
	return []string{sql}
}

// 删除列
func (this Mysql) CompileDropColumn(bp *schema.Blueprint) []string {
	columns := []string{}

	for _, item := range bp.GetCommands() {
		if item.Type != "dropColumn" {
			continue
		}
		for _, col := range item.Columns {
			columns = append(columns, this.GenerateSQL("DROP COLUMN ?", db.C(col)))
		}
	}

	sql := this.GenerateSQL("ALTER TABLE ?\n?", db.T(bp.GetTable()), db.L(strings.Join(columns, ",\n")))
	return []string{sql}
}

// 删除表
func (this Mysql) CompileDrop(bp *schema.Blueprint) []string {
	return []string{this.GenerateSQL("DROP TABLE ?", db.T(bp.GetTable()))}
}

// 删除表, 先判断再删除
func (this Mysql) CompileDropIfExists(bp *schema.Blueprint) []string {
	return []string{this.GenerateSQL("DROP TABLE IF EXISTS ?", db.T(bp.GetTable()))}
}

// 表重命名
func (this Mysql) CompileRename(bp *schema.Blueprint) []string {
	toName := ""
	commands := bp.GetCommands()
	if len(commands) == 0 {
		panic("new table undefined")
	}
	toName = bp.GetCommands()[0].To
	if toName == "" {
		panic("new table undefined")
	}
	return []string{this.GenerateSQL("RENAME TABLE ? TO ?", db.T(bp.GetTable()), db.T(toName))}
}

func (this Mysql) addModifiers(sql string, bp *schema.Blueprint, column *schema.ColumnDefinition) string {
	for _, modifier := range mysqlDefaultModifiers {
		sql += this.GetColumnModifier(modifier, bp, column)
	}
	return sql
}

func (this Mysql) GetColumnType(column *schema.ColumnDefinition) string {
	switch column.Type {
	case "char":
		return this.GenerateSQL("char(?)", column.Length)
	case "string":
		return this.GenerateSQL("varchar(?)", column.Length)
	case "text":
		return "text"
	case "integer":
		return this.GenerateSQL("int(?)", column.Length)
	case "bigInteger":
		return "bigint(20)"
	case "tinyInteger":
		return "tinyint(1)"
	case "smallInteger":
		return "smallint(4)"
	case "decimal":
		return this.GenerateSQL("decimal(?,?)", column.Total, column.Places)
	case "boolean":
		return "tinyint(1)"
	case "enum":
		return this.GenerateSQL("enum?", column.Allowed)
	case "json":
		return "json"
	case "binary":
		return "binary"
	case "datetime":
		return "datetime"
	case "timestamp":
		return "timestamp"
	case "date":
		return "date"
	case "time":
		return "time"
	case "year":
		return "year"
	case "uuid":
		return "char(36)"
	}
	panic("Unsupported data type: " + column.Type)
}

func (this Mysql) GetColumnModifier(modifier string, bp *schema.Blueprint, column *schema.ColumnDefinition) string {
	switch modifier {
	case "Unsigned":
		if column.IsUnsigned() {
			return " UNSIGNED"
		}
	case "Charset":
		if v := column.GetCharset(); v != "" {
			return this.GenerateSQL(" CHARACTER SET ?", v)
		}
	case "Collate":
		if v := column.GetCollaction(); v != "" {
			return this.GenerateSQL(" COLLATE ?", v)
		}
	case "VirtualAs":
		if v := column.GetVirtualAs(); v != "" {
			return this.GenerateSQL(" GENERATED ALWAYS AS (?) VIRTUAL", db.L(v))
		}
	case "StoredAs":
		if v := column.GetStoredAs(); v != "" {
			return this.GenerateSQL(" GENERATED ALWAYS AS (?) STORED", db.L(v))
		}
	case "Nullable":
		if column.GetVirtualAs() == "" && column.GetStoredAs() == "" {
			if column.IsNullable() {
				return " NULL"
			}
			return " NOT NULL"
		}
	case "Default":
		v := column.GetDefault()
		if v == nil {
			if column.IsUseCurrent() {
				return " DEFAULT CURRENT_TIMESTAMP"
			}
			return ""
		}
		if column.IsUseCurrent() {
			return this.GenerateSQL(" DEFAULT CURRENT_TIMESTAMP ?", v)
		}
		return this.GenerateSQL(" DEFAULT ?", v)
	case "Increment":
		if column.IsAutoIncrement() {
			return " AUTO_INCREMENT PRIMARY KEY"
		}
	case "Comment":
		if v := column.GetComment(); v != "" {
			return this.GenerateSQL(" COMMENT ?", v)
		}
	case "After":
		if v := column.GetAfter(); v != "" {
			return this.GenerateSQL(" AFTER ?", v)
		}
	case "First":
		if column.IsFirst() {
			return " FIRST"
		}
	}
	return ""
}

// 获取新增表结构字段
func (this Mysql) getAddedColumns(bp *schema.Blueprint) (columns []string) {
	for _, column := range bp.GetAddedColumns() {
		sql := this.GenerateSQL("? ?", db.C(column.Name), db.L(this.GetColumnType(column)))
		columns = append(columns, this.addModifiers(sql, bp, column))
	}
	return
}

// 获取修改表结构字段
func (this Mysql) getChangedColumns(bp *schema.Blueprint) (columns []string) {
	for _, column := range bp.GetChangedColumns() {
		name := column.Name
		rename := column.Name
		if column.GetRename() != "" {
			rename = column.GetRename()
		}
		sql := this.GenerateSQL("? ? ?", db.C(name), db.C(rename), db.L(this.GetColumnType(column)))
		columns = append(columns, this.addModifiers(sql, bp, column))
	}
	return
}

// 生成SQL
func (this Mysql) GenerateSQL(sql string, args ...any) string {
	sb := sb.NewSQLBuilder(false)
	this.esg.Generate(sb, db.L(sql, args...))
	result, _, _ := sb.ToSQL()
	return result
}

func init() {
	schema.RegisterDialect("mysql", func(db *db.Database) schema.Schema {
		return &Mysql{
			db:  db,
			esg: sqlgen.NewExpressionSQLGenerator("mysql", mysql.DialectOptions()),
		}
	})
}