package store

import (
	"database/sql"
	"errors"
	"time"
)

var ErrInstanceLimit = errors.New("instance limit reached")
var ErrIntentState = errors.New("intent is no longer waiting")

type Intent struct {
	ID         string `json:"id"`
	UID        string `json:"uid"`
	Name       string `json:"name"`
	Version    string `json:"version"`
	BuildID    string `json:"build_id"`
	InstanceID string `json:"instance_id"`
	Status     string `json:"status"`
	Error      string `json:"error"`
	Host       string `json:"-"`
	Created    int64  `json:"created_at"`
}

func (s *Store) EnsureIntents() error {
	_, err := s.DB.Exec(`CREATE TABLE IF NOT EXISTS creation_intents(id TEXT PRIMARY KEY,uid TEXT NOT NULL,name TEXT NOT NULL,version TEXT NOT NULL,build_id TEXT NOT NULL DEFAULT '',instance_id TEXT NOT NULL DEFAULT '',status TEXT NOT NULL,error TEXT NOT NULL DEFAULT '',host TEXT NOT NULL,created INTEGER NOT NULL); CREATE INDEX IF NOT EXISTS intents_owner ON creation_intents(uid,status);`)
	return err
}

func reserveSlot(tx *sql.Tx, uid string) error {
	var count int
	if err := tx.QueryRow(`SELECT (SELECT count(*) FROM instances WHERE uid=?) + (SELECT count(*) FROM creation_intents WHERE uid=? AND status='waiting')`, uid, uid).Scan(&count); err != nil {
		return err
	}
	if count >= 2 {
		return ErrInstanceLimit
	}
	return nil
}

func (s *Store) ReserveIntent(i Intent) error {
	tx, err := s.DB.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()
	if err = reserveSlot(tx, i.UID); err != nil {
		return err
	}
	_, err = tx.Exec(`INSERT INTO creation_intents(id,uid,name,version,status,host,created) VALUES(?,?,?,?,'waiting',?,?)`, i.ID, i.UID, i.Name, i.Version, i.Host, time.Now().Unix())
	if err != nil {
		return err
	}
	return tx.Commit()
}

func (s *Store) ReserveInstance(i Instance) error {
	tx, err := s.DB.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()
	if err = reserveSlot(tx, i.UID); err != nil {
		return err
	}
	if err = insertInstance(tx, i); err != nil {
		return err
	}
	return tx.Commit()
}
func insertInstance(tx *sql.Tx, i Instance) error {
	_, err := tx.Exec(`INSERT INTO instances VALUES(?,?,?,?,?,?,?,?)`, i.ID, i.UID, i.Name, i.Version, i.ImageID, i.Status, i.ContainerID, time.Now().Unix())
	return err
}
func (s *Store) ClaimIntent(id string, i Instance) error {
	tx, err := s.DB.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()
	result, err := tx.Exec(`UPDATE creation_intents SET status='creating',instance_id=? WHERE id=? AND uid=? AND version=? AND status='waiting'`, i.ID, id, i.UID, i.Version)
	if err != nil {
		return err
	}
	n, err := result.RowsAffected()
	if err != nil {
		return err
	}
	if n != 1 {
		return ErrIntentState
	}
	if err = insertInstance(tx, i); err != nil {
		return err
	}
	return tx.Commit()
}
func (s *Store) CancelIntent(id, uid string) error {
	r, err := s.DB.Exec(`UPDATE creation_intents SET status='cancelled' WHERE id=? AND uid=? AND status='waiting'`, id, uid)
	if err != nil {
		return err
	}
	n, err := r.RowsAffected()
	if err != nil {
		return err
	}
	if n != 1 {
		return ErrIntentState
	}
	return nil
}
func (s *Store) Intents(uid string) ([]Intent, error) {
	query := `SELECT id,uid,name,version,build_id,instance_id,status,error,host,created FROM creation_intents`
	var args []any
	if uid != "" {
		query += ` WHERE uid=?`
		args = append(args, uid)
	}
	query += ` ORDER BY created,id`
	rows, err := s.DB.Query(query, args...)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	out := []Intent{}
	for rows.Next() {
		var i Intent
		if err = rows.Scan(&i.ID, &i.UID, &i.Name, &i.Version, &i.BuildID, &i.InstanceID, &i.Status, &i.Error, &i.Host, &i.Created); err != nil {
			return nil, err
		}
		out = append(out, i)
	}
	return out, rows.Err()
}