// Package actor provides database access for the Actor resource.
// It defines the DBActor struct and ActorTranslator to convert between
// the API format (api.pb.go) and the database format (schema.sql).
package actor

import (
	"database/sql"
	"errors"
	"fmt"
	"regexp"
	"strings"
	"time"

	v1 "git.tipsy.codes/charles/webstory/pkg/api/webstory/v1"
	"github.com/google/uuid"
	"github.com/lib/pq"
	"google.golang.org/protobuf/types/known/timestamppb"
)

var (
	// ErrActorIDInvalid is returned when the actor_id format is invalid.
	ErrActorIDInvalid = errors.New("invalid actor_id format: must be 4-63 characters, matching pattern /[a-z][0-9-]/")

	// actorIDPattern validates the actor_id format.
	actorIDPattern = regexp.MustCompile(`^[a-z][0-9a-z-]{2,61}[0-9a-z]$`)
)

// DBActor represents an actor in the PostgreSQL database.
type DBActor struct {
	ID        int64
	StoryID   int64
	ActorID   string
	NameValue string
	Role      string
	Notes     string
	CreatedAt time.Time
	UpdatedAt time.Time
	Etag      string
}

// ActorTranslator provides conversion methods between API and database formats.
type ActorTranslator struct{}

func NewActorTranslator() *ActorTranslator {
	return &ActorTranslator{}
}

func (t *ActorTranslator) FromAPI(apiActor *v1.Actor) (*DBActor, error) {
	if apiActor == nil {
		return nil, errors.New("api actor cannot be nil")
	}

	if apiActor.ActorId != "" {
		if err := validateActorID(apiActor.ActorId); err != nil {
			return nil, err
		}
	}

	if apiActor.NameValue == "" {
		return nil, errors.New("name_value is required")
	}

	var createdAt, updatedAt time.Time
	if apiActor.GetCreateTime() != nil {
		createdAt = apiActor.CreateTime.AsTime()
	}
	if apiActor.GetUpdateTime() != nil {
		updatedAt = apiActor.UpdateTime.AsTime()
	}

	return &DBActor{
		ID:        0,
		StoryID:   0,
		ActorID:   apiActor.ActorId,
		NameValue: apiActor.NameValue,
		Role:      apiActor.Role,
		Notes:     apiActor.Notes,
		CreatedAt: createdAt,
		UpdatedAt: updatedAt,
		Etag:      apiActor.Etag,
	}, nil
}

func (t *ActorTranslator) ToAPI(dbActor *DBActor) *v1.Actor {
	if dbActor == nil {
		return nil
	}

	name := ""
	if dbActor.StoryID > 0 && dbActor.ActorID != "" {
		name = fmt.Sprintf("stories/%d/actors/%s", dbActor.StoryID, dbActor.ActorID)
	}

	return &v1.Actor{
		Name:        name,
		ActorId:     dbActor.ActorID,
		NameValue:   dbActor.NameValue,
		Role:        dbActor.Role,
		Notes:       dbActor.Notes,
		CreateTime:  timestamppb.New(dbActor.CreatedAt),
		UpdateTime:  timestamppb.New(dbActor.UpdatedAt),
		Etag:        dbActor.Etag,
	}
}

func (t *ActorTranslator) ToAPIDetailed(dbActor *DBActor, storyID int64) *v1.Actor {
	apiActor := t.ToAPI(dbActor)
	if dbActor.StoryID > 0 {
		apiActor.Name = fmt.Sprintf("stories/%d/actors/%s", dbActor.StoryID, dbActor.ActorID)
	}
	return apiActor
}

func (a *DBActor) Validate() error {
	if a.ActorID == "" {
		return errors.New("actor_id is required")
	}
	if a.NameValue == "" {
		return errors.New("name_value is required")
	}
	if a.StoryID <= 0 {
		return errors.New("story_id is required")
	}
	if err := validateActorID(a.ActorID); err != nil {
		return err
	}
	return nil
}

func validateActorID(actorID string) error {
	if actorID == "" {
		return ErrActorIDInvalid
	}
	if len(actorID) < 4 || len(actorID) > 63 {
		return ErrActorIDInvalid
	}
	if !actorIDPattern.MatchString(actorID) {
		return ErrActorIDInvalid
	}
	return nil
}

func (a *DBActor) Save(db *sql.DB) error {
	if err := a.Validate(); err != nil {
		return err
	}

	if a.ID > 0 {
		return a.update(db)
	}
	return a.insert(db)
}

func (a *DBActor) insert(db *sql.DB) error {
	query := `
		INSERT INTO actors (story_id, actor_id, name_value, role, notes, created_at, updated_at, etag)
		VALUES ($1, $2, $3, $4, $5, $6, $7, $8)
		RETURNING id, created_at, updated_at, etag
	`

	now := time.Now()
	if a.CreatedAt.IsZero() {
		a.CreatedAt = now
	}
	if a.UpdatedAt.IsZero() {
		a.UpdatedAt = now
	}

	etag := a.Etag
	if etag == "" {
		etag = generateEtag()
	}

	var createdID int64
	var createdAt, updatedAt time.Time
	var returnedEtag string

	err := db.QueryRow(
		query,
		a.StoryID,
		a.ActorID,
		a.NameValue,
		pq.Array([]string{a.Role}),
		pq.Array([]string{a.Notes}),
		a.CreatedAt,
		a.UpdatedAt,
		etag,
	).Scan(&createdID, &createdAt, &updatedAt, &returnedEtag)

	if err != nil {
		return fmt.Errorf("failed to insert actor: %w", err)
	}

	a.ID = createdID
	a.CreatedAt = createdAt
	a.UpdatedAt = updatedAt
	a.Etag = returnedEtag

	return nil
}

func (a *DBActor) update(db *sql.DB) error {
	query := `
		UPDATE actors
		SET name_value = $1,
		    role = $2,
		    notes = $3,
		    updated_at = $4,
		    etag = $5
		WHERE id = $6
		RETURNING created_at, updated_at, etag
	`

	now := time.Now()
	if a.UpdatedAt.IsZero() {
		a.UpdatedAt = now
	}

	etag := a.Etag
	if etag == "" {
		etag = generateEtag()
	}

	var createdAt, updatedAt time.Time
	var returnedEtag string

	err := db.QueryRow(
		query,
		a.NameValue,
		a.Role,
		a.Notes,
		a.UpdatedAt,
		etag,
		a.ID,
	).Scan(&createdAt, &updatedAt, &returnedEtag)

	if err != nil {
		return fmt.Errorf("failed to update actor: %w", err)
	}

	a.CreatedAt = createdAt
	a.UpdatedAt = updatedAt
	a.Etag = returnedEtag

	return nil
}

func generateEtag() string {
	return uuid.New().String()
}

func GetByID(db *sql.DB, id int64) (*DBActor, error) {
	query := `
		SELECT id, story_id, actor_id, name_value, role, notes, created_at, updated_at, etag
		FROM actors
		WHERE id = $1
	`

	actor := &DBActor{}
	err := db.QueryRow(query, id).Scan(
		&actor.ID,
		&actor.StoryID,
		&actor.ActorID,
		&actor.NameValue,
		&actor.Role,
		&actor.Notes,
		&actor.CreatedAt,
		&actor.UpdatedAt,
		&actor.Etag,
	)

	if err != nil {
		if err == sql.ErrNoRows {
			return nil, fmt.Errorf("actor with id %d not found", id)
		}
		return nil, fmt.Errorf("failed to get actor: %w", err)
	}

	return actor, nil
}

func GetByActorID(db *sql.DB, storyID int64, actorID string) (*DBActor, error) {
	if err := validateActorID(actorID); err != nil {
		return nil, err
	}

	query := `
		SELECT id, story_id, actor_id, name_value, role, notes, created_at, updated_at, etag
		FROM actors
		WHERE story_id = $1 AND actor_id = $2
	`

	actor := &DBActor{}
	err := db.QueryRow(query, storyID, actorID).Scan(
		&actor.ID,
		&actor.StoryID,
		&actor.ActorID,
		&actor.NameValue,
		&actor.Role,
		&actor.Notes,
		&actor.CreatedAt,
		&actor.UpdatedAt,
		&actor.Etag,
	)

	if err != nil {
		if err == sql.ErrNoRows {
			return nil, fmt.Errorf("actor with story_id %d and actor_id '%s' not found", storyID, actorID)
		}
		return nil, fmt.Errorf("failed to get actor: %w", err)
	}

	return actor, nil
}

func ListByStoryID(db *sql.DB, storyID int64) ([]*DBActor, error) {
	if storyID <= 0 {
		return nil, errors.New("story_id must be positive")
	}

	query := `
		SELECT id, story_id, actor_id, name_value, role, notes, created_at, updated_at, etag
		FROM actors
		WHERE story_id = $1
		ORDER BY name_value ASC
	`

	rows, err := db.Query(query, storyID)
	if err != nil {
		return nil, fmt.Errorf("failed to list actors: %w", err)
	}
	defer rows.Close()

	actors := make([]*DBActor, 0)
	for rows.Next() {
		var id int64
		var storyID int64
		var actorID, nameValue, role, notes string
		var createdAt, updatedAt time.Time
		var etag string

		err := rows.Scan(&id, &storyID, &actorID, &nameValue, &role, &notes, &createdAt, &updatedAt, &etag)
		if err != nil {
			return nil, fmt.Errorf("failed to scan actor: %w", err)
		}

		actors = append(actors, &DBActor{
			ID:        id,
			StoryID:   storyID,
			ActorID:   actorID,
			NameValue: nameValue,
			Role:      role,
			Notes:     notes,
			CreatedAt: createdAt,
			UpdatedAt: updatedAt,
			Etag:      etag,
		})
	}

	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("error iterating actors: %w", err)
	}

	return actors, nil
}

func Delete(db *sql.DB, id int64) error {
	query := `
		DELETE FROM actors
		WHERE id = $1
	`

	result, err := db.Exec(query, id)
	if err != nil {
		return fmt.Errorf("failed to delete actor: %w", err)
	}

	rowsAffected, err := result.RowsAffected()
	if err != nil {
		return fmt.Errorf("failed to get rows affected: %w", err)
	}

	if rowsAffected == 0 {
		return fmt.Errorf("actor with id %d not found", id)
	}

	return nil
}

func GetActorIDForResourceName(resourceName string) (int64, string, error) {
	prefix := "stories/"
	if !strings.HasPrefix(resourceName, prefix) {
		return 0, "", fmt.Errorf("invalid resource name: must start with '%s', got '%s'", prefix, resourceName)
	}

	remaining := strings.TrimPrefix(resourceName, prefix)

	actorPrefix := "actors/"
	if !strings.HasPrefix(remaining, actorPrefix) {
		return 0, "", fmt.Errorf("invalid actor resource name: must contain '%s', got '%s'", actorPrefix, remaining)
	}

	actorID := strings.TrimPrefix(remaining, actorPrefix)
	if actorID == "" {
		return 0, "", errors.New("actor_id is empty in resource name")
	}

	if err := validateActorID(actorID); err != nil {
		return 0, "", fmt.Errorf("invalid actor_id in resource name: %w", err)
	}

	storyPart := strings.TrimSuffix(remaining, actorPrefix+actorID)
	if storyPart == "" {
		return 0, "", errors.New("story_id is missing from resource name")
	}

	var storyID int64
	_, err := fmt.Sscanf(storyPart, "%d", &storyID)
	if err != nil || storyID <= 0 {
		return 0, "", errors.New("invalid story_id in resource name")
	}

	return storyID, actorID, nil
}