package db

import (
	"fmt"
	"strings"

	"github.com/jmoiron/sqlx"

	"git.offline-twitter.com/offline-labs/gas-stack/pkg/must"
)

// PragmaFKViolation is a result row of SQLite's `pragma foreign_key_check`.
type PragmaFKViolation struct {
	SrcTable      string `db:"table"`
	SrcRowid      int    `db:"rowid"`
	DstTable      string `db:"parent"`
	ForeignKeyIdx int    `db:"fkid"`
}

// PragmaFKViolations is a slice of FK violations.  It also implements the `error` interface.
type PragmaFKViolations []PragmaFKViolation

func (v PragmaFKViolations) Error() string {
	var b strings.Builder
	for i, fkv := range v {
		if i > 0 {
			b.WriteString("\n")
		}
		fmt.Fprintf(&b, "Item #%d in table %q has invalid reference to table %q", fkv.SrcRowid, fkv.SrcTable, fkv.DstTable)
	}
	return b.String()
}

// PragmaForeignKeyCheck uses `pragma foreign_key_check` to do a full database check for any FK violations.
func PragmaForeignKeyCheck(q sqlx.Queryer) error {
	var ret PragmaFKViolations
	must.Do(sqlx.Select(q, &ret, `pragma foreign_key_check`))
	if len(ret) == 0 {
		return nil
	}
	return ret
}