package cache

import (
	"fmt"
	"io"
	"strconv"

	"github.com/git-bug/git-bug/entity"
)

type BuildEventType int

const (
	_ BuildEventType = iota
	// BuildEventCacheIsBuilt signal that the cache is being built (aka, not skipped)
	BuildEventCacheIsBuilt
	// BuildEventRemoveLock signal that an old repo lock has been cleaned
	BuildEventRemoveLock
	// BuildEventStarted signal the beginning of a cache build for an entity
	BuildEventStarted
	// BuildEventProgress signal progress in the cache building for an entity
	BuildEventProgress
	// BuildEventFinished signal the end of a cache build for an entity
	BuildEventFinished
)

// BuildEvent carry an event happening during the cache build process.
type BuildEvent struct {
	// Err carry an error if the build process failed. If set, no other field matters.
	Err error
	// Typename is the name of the entity of which the event relate to. Can be empty if no particular entity is involved.
	Typename string
	// Event is the type of the event.
	Event BuildEventType
	// Total is the total number of elements being built. Set if Event is BuildEventStarted.
	Total int64
	// Progress is the current count of processed elements. Set if Event is BuildEventProgress.
	Progress int64
}

type EntityEventType int

const (
	_ EntityEventType = iota
	EntityEventCreated
	EntityEventUpdated
	EntityEventRemoved
)

// Observer gets notified of changes in entities in the cache
type Observer interface {
	EntityEvent(event EntityEventType, repoName string, typename string, id entity.Id)
}

func (e EntityEventType) MarshalGQL(w io.Writer) {
	switch e {
	case EntityEventCreated:
		_, _ = w.Write([]byte(strconv.Quote("CREATED")))
	case EntityEventUpdated:
		_, _ = w.Write([]byte(strconv.Quote("UPDATED")))
	case EntityEventRemoved:
		_, _ = w.Write([]byte(strconv.Quote("REMOVED")))
	default:
		panic("missing case")
	}
}

func (e *EntityEventType) UnmarshalGQL(v interface{}) error {
	str, ok := v.(string)
	if !ok {
		return fmt.Errorf("enums must be strings")
	}
	switch str {
	case "CREATED":
		*e = EntityEventCreated
	case "UPDATED":
		*e = EntityEventUpdated
	case "REMOVED":
		*e = EntityEventRemoved
	default:
		return fmt.Errorf("%s is not a valid EntityEventType", str)
	}
	return nil
}