package sqlite3

import (
	"fmt"
	"strings"
	"time"

	"git.fsdpf.net/go/db"
	"git.fsdpf.net/go/db/dialect/sqlite3"
	"git.fsdpf.net/go/db/internal/sb"
	"git.fsdpf.net/go/db/schema"
	"git.fsdpf.net/go/db/sqlgen"
)

var (
	sqlite3DefaultModifiers = []string{"Hidden", "Nullable", "Default", "Increment"}
	sqlite3Serials          = []string{"bigInteger", "integer", "mediumInteger", "smallInteger", "tinyInteger"}
)

type Sqlite3 struct {
	db  *db.Database
	esg sqlgen.ExpressionSQLGenerator
}

// 判断表是否存在
func (this Sqlite3) TableExists(table string) (bool, error) {
	result, err := this.db.From(db.T("sqlite_master")).Where(db.Ex{
		"name": table,
		"type": "table",
	}).Count()
	return result > 0, err
}

// 字段列
func (this Sqlite3) GetColumnListing(table string) ([]string, error) {
	cols := []struct {
		Cid       string `db:"cid"`
		Name      string `db:"name"`
		Type      string `db:"type"`
		Notnull   int32  `db:"notnull"`
		DfltValue string `db:"dflt_value"`
		Pk        string `db:"pk"`
	}{}

	err := this.db.ScanStructs(&cols, "PRAGMA table_info(entry)")

	columns := []string{}

	for _, item := range cols {
		columns = append(columns, item.Name)
	}

	return columns, err
}

// 创建表
func (this Sqlite3) CompileCreate(bp *schema.Blueprint) (sqls []string) {
	temporary := db.L("CREATE")
	columns := []string{}

	count := len(bp.GetAddedColumns()) - 1
	for i, column := range bp.GetAddedColumns() {
		sql := this.GenerateSQL(this.addModifiers("? ? ", bp, column),
			db.C(column.Name),
			db.L(this.GetColumnType(column)),
		)
		if v := column.GetComment(); v != "" {
			if i != count {
				sql += ","
			}
			sql += " -- " + v
		}
		columns = append(columns, sql)
	}

	prefix := "? TABLE IF NOT EXISTS ? (\n?\n)"

	if comment := bp.Comment; comment != "" {
		prefix = "? TABLE IF NOT EXISTS ? ( -- " + comment + "\n?\n)"
	}

	sqls = append(sqls,
		this.GenerateSQL(prefix,
			temporary,
			db.T(bp.GetTable()),
			db.L(strings.Join(columns, "\n")),
		),
	)
	return sqls
}

// 添加字段
func (this Sqlite3) CompileAdd(bp *schema.Blueprint) (sqls []string) {
	for _, column := range bp.GetAddedColumns() {
		sqls = append(sqls, this.addModifiers(
			this.GenerateSQL("ALTER TABLE ? ADD COLUMN ? ? ",
				db.T(bp.GetTable()),
				db.C(column.Name),
				db.L(this.GetColumnType(column)),
			), bp, column),
		)
	}
	return sqls
}

// 修改字段
func (this Sqlite3) CompileChange(bp *schema.Blueprint) (sqls []string) {
	for _, column := range bp.GetChangedColumns() {
		name := column.Name
		rename := column.Name
		old_name := fmt.Sprintf("%s_%d", name, time.Now().UnixNano())

		sql := this.GenerateSQL("ALTER TABLE ? ADD COLUMN ? ? ", db.T(bp.GetTable()), db.C(old_name), db.L(this.GetColumnType(column)))
		sqls = append(sqls, this.addModifiers(sql, bp, column))
		if name := column.GetRename(); name != "" {
			rename = name
		}
		sqls = append(sqls, this.GenerateSQL("UPDATE ? SET ?=?", db.T(bp.GetTable()), db.C(old_name), db.C(name)))
		sqls = append(sqls, this.GenerateSQL("ALTER TABLE ? DROP COLUMN ?", db.T(bp.GetTable()), db.C(name)))
		sqls = append(sqls, this.GenerateSQL("ALTER TABLE ? RENAME COLUMN ? TO ?", db.T(bp.GetTable()), db.T(old_name), db.T(rename)))
	}
	return sqls
}

// 删除表
func (this Sqlite3) 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 Sqlite3) CompileDropIfExists(bp *schema.Blueprint) []string {
	return []string{this.GenerateSQL("DROP TABLE IF EXISTS ?", db.T(bp.GetTable()))}
}

// 删除表, 删除列
func (this Sqlite3) CompileDropColumn(bp *schema.Blueprint) (sqls []string) {
	for _, item := range bp.GetCommands() {
		if item.Type != "dropColumn" {
			continue
		}
		for _, col := range item.Columns {
			sqls = append(sqls, this.GenerateSQL("ALTER TABLE ? DROP COLUMN ?", db.T(bp.GetTable()), db.C(col)))
		}
	}
	return sqls
}

// 表重命名
func (this Sqlite3) 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))}
}

// 修改表备注
func (this Sqlite3) CompileModifyComment(bp *schema.Blueprint) []string {
	return []string{}
}

func (this Sqlite3) GetColumnModifier(modifier string, bp *schema.Blueprint, column *schema.ColumnDefinition) string {
	switch modifier {
	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 "Hidden":
		if column.IsHidden() {
			return "HIDDEN"
		}
	case "Nullable":
		// HIDDEN 列和生成列不加 NULL/NOT NULL
		if column.GetVirtualAs() == "" && column.GetStoredAs() == "" && !column.IsHidden() {
			if column.IsNullable() {
				return "NULL"
			}
			return "NOT NULL"
		}
	case "Default":
		if column.IsHidden() {
			return ""
		}
		if column.IsUseCurrent() {
			return " DEFAULT CURRENT_TIMESTAMP"
		}
		v := column.GetDefault()
		if v == nil {
			return ""
		}
		return this.GenerateSQL(" DEFAULT ?", v)
	case "Increment":
		if column.IsAutoIncrement() {
			return " PRIMARY KEY AUTOINCREMENT"
		}
	case "Comment":
		if v := column.GetComment(); v != "" {
			return this.GenerateSQL(" COMMENT ?", v)
		}
	}
	return ""
}

func (this Sqlite3) GetColumnType(column *schema.ColumnDefinition) string {
	if column.IsAutoIncrement() {
		return "INTEGER"
	}
	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":
		if column.Length > 0 {
			return this.GenerateSQL("INTEGER(?)", column.Length)
		}
		return "INTEGER"
	case "bigInteger":
		return "bigint(20)"
	case "tinyInteger":
		return "tinyint(1)"
	case "smallInteger":
		return "smallint(4)"
	case "decimal":
		return this.GenerateSQL("numeric(?,?)", column.Total, column.Places)
	case "boolean":
		return "tinyint(1)"
	case "enum":
		return this.GenerateSQL("varchar check(? in?)", column.Name, 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)"
	case "vector":
		return this.GenerateSQL("float[?]", column.Length)
	}
	panic("Unsupported data type: " + column.Type)
}

func (this Sqlite3) addModifiers(sql string, bp *schema.Blueprint, column *schema.ColumnDefinition) string {
	for _, modifier := range sqlite3DefaultModifiers {
		sql += this.GetColumnModifier(modifier, bp, column)
	}
	return sql
}

// 生成SQL
func (this Sqlite3) 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() {
	sc := func(db *db.Database) schema.Schema {
		return &Sqlite3{
			db:  db,
			esg: sqlgen.NewExpressionSQLGenerator("sqlite3", sqlite3.DialectOptions()),
		}
	}

	schema.RegisterDialect("sqlite3", sc)
	schema.RegisterDialect("vtable", sc)
}