package resource

import (
	"fmt"
	"strings"

	"gorm.io/gorm"
	"gorm.io/gorm/clause"
	"gorm.io/gorm/migrator"
	"gorm.io/gorm/schema"
)

// fix primary key autoincrement problem
type sqliteDialector struct {
	gorm.Dialector
}

func (dialector *sqliteDialector) DataTypeOf(field *schema.Field) string {
	switch field.DataType {
	case schema.Int, schema.Uint:
		if field.AutoIncrement {
			// https://www.sqlite.org/autoinc.html
			return "integer PRIMARY KEY AUTOINCREMENT"
		}
	}

	return dialector.Dialector.DataTypeOf(field)
}

func (dialector *sqliteDialector) Migrator(db *gorm.DB) gorm.Migrator {
	return sqliteMigrator{innerSQLiteMigrator{Migrator: migrator.Migrator{Config: migrator.Config{
		DB:                          db,
		Dialector:                   dialector,
		CreateIndexAfterCreateTable: true,
	}}}}
}

type sqliteMigrator struct {
	innerSQLiteMigrator
}

// CreateTable create table in database for values
func (m sqliteMigrator) CreateTable(values ...interface{}) error {
	for _, value := range m.ReorderModels(values, false) {
		tx := m.DB.Session(&gorm.Session{})
		if err := m.RunWithValue(value, func(stmt *gorm.Statement) (err error) {
			var (
				createTableSQL          = "CREATE TABLE ? ("
				values                  = []interface{}{m.CurrentTable(stmt)}
				hasPrimaryKeyInDataType bool
			)

			for _, dbName := range stmt.Schema.DBNames {
				field := stmt.Schema.FieldsByDBName[dbName]
				if !field.IgnoreMigration {
					createTableSQL += "? ?"
					hasPrimaryKeyInDataType = hasPrimaryKeyInDataType || strings.Contains(strings.ToUpper(m.DataTypeOf(field)), "PRIMARY KEY")
					values = append(values, clause.Column{Name: dbName}, m.DB.Migrator().FullDataTypeOf(field))
					createTableSQL += ","
				}
			}

			if !hasPrimaryKeyInDataType && len(stmt.Schema.PrimaryFields) > 0 {
				createTableSQL += "PRIMARY KEY ?,"
				primaryKeys := make([]interface{}, 0, len(stmt.Schema.PrimaryFields))
				for _, field := range stmt.Schema.PrimaryFields {
					primaryKeys = append(primaryKeys, clause.Column{Name: field.DBName})
				}

				values = append(values, primaryKeys)
			}

			for _, idx := range stmt.Schema.ParseIndexes() {
				if m.CreateIndexAfterCreateTable {
					defer func(value interface{}, name string) {
						if err == nil {
							err = tx.Migrator().CreateIndex(value, name)
						}
					}(value, idx.Name)
				} else {
					if idx.Class != "" {
						createTableSQL += idx.Class + " "
					}
					createTableSQL += "INDEX ? ?"

					if idx.Comment != "" {
						createTableSQL += fmt.Sprintf(" COMMENT '%s'", idx.Comment)
					}

					if idx.Option != "" {
						createTableSQL += " " + idx.Option
					}

					createTableSQL += ","
					values = append(values, clause.Column{Name: idx.Name}, tx.Migrator().(migrator.BuildIndexOptionsInterface).BuildIndexOptions(idx.Fields, stmt))
				}
			}

			if !m.DB.DisableForeignKeyConstraintWhenMigrating && !m.DB.IgnoreRelationshipsWhenMigrating {
				for _, rel := range stmt.Schema.Relationships.Relations {
					if rel.Field.IgnoreMigration {
						continue
					}
					if constraint := rel.ParseConstraint(); constraint != nil {
						if constraint.Schema == stmt.Schema {
							sql, vars := buildConstraint(constraint)
							createTableSQL += sql + ","
							values = append(values, vars...)
						}
					}
				}
			}

			for _, chk := range stmt.Schema.ParseCheckConstraints() {
				createTableSQL += "CONSTRAINT ? CHECK (?),"
				values = append(values, clause.Column{Name: chk.Name}, clause.Expr{SQL: chk.Constraint})
			}

			createTableSQL = strings.TrimSuffix(createTableSQL, ",")

			createTableSQL += ")"

			if tableOption, ok := m.DB.Get("gorm:table_options"); ok {
				createTableSQL += fmt.Sprint(tableOption)
			}

			err = tx.Exec(createTableSQL, values...).Error
			return err
		}); err != nil {
			return err
		}
	}
	return nil
}

func buildConstraint(constraint *schema.Constraint) (sql string, results []interface{}) {
	sql = "CONSTRAINT ? FOREIGN KEY ? REFERENCES ??"
	if constraint.OnDelete != "" {
		sql += " ON DELETE " + constraint.OnDelete
	}

	if constraint.OnUpdate != "" {
		sql += " ON UPDATE " + constraint.OnUpdate
	}

	var foreignKeys, references []interface{}
	for _, field := range constraint.ForeignKeys {
		foreignKeys = append(foreignKeys, clause.Column{Name: field.DBName})
	}

	for _, field := range constraint.References {
		references = append(references, clause.Column{Name: field.DBName})
	}
	results = append(results, clause.Table{Name: constraint.Name}, foreignKeys, clause.Table{Name: constraint.ReferenceSchema.Table}, references)
	return
}