package controllers

import (
	"context"
	"errors"
	"fmt"
	"strconv"

	"git.golem15.com/golem15/sm-journal-plugin/console"
	"git.golem15.com/golem15/sm-journal-plugin/models"
	"git.golem15.com/golem15/summercms/modules/backpack"
	"git.golem15.com/golem15/summercms/modules/bouncer"
	"git.golem15.com/golem15/summercms/modules/cabana"
	"git.golem15.com/golem15/summercms/modules/pact"
	"gorm.io/gorm"
)

const (
	// PostsControllerID is the cabana controller id of the Posts screen.
	PostsControllerID = "golem15.journal.posts"

	// PermissionAccessPosts is Posts::$requiredPermissions.
	PermissionAccessPosts = "golem15.journal.access_posts"
	// PermissionAccessOtherPosts lets an administrator see every author's posts.
	PermissionAccessOtherPosts = "golem15.journal.access_other_posts"
	// PermissionAccessPublish is required to persist published=true or published_at.
	PermissionAccessPublish = "golem15.journal.access_publish"
	// PermissionAccessImportExport gates journal:export-posts / import-posts
	// toolbar actions (D-13).
	PermissionAccessImportExport = "golem15.journal.access_import_export"
)

type postsAdminController struct {
	app func() *backpack.App
}

func (postsAdminController) ID() string { return PostsControllerID }

func (postsAdminController) ModelName() string { return `Golem15\Journal\Models\Post` }

func (postsAdminController) ConfigDir() string { return "controllers/posts" }

func (postsAdminController) RequiredPermissions() []string {
	return []string{PermissionAccessPosts}
}

func (postsAdminController) NewRecord() any { return &models.Post{} }

func (c postsAdminController) application() *backpack.App {
	if c.app == nil {
		return nil
	}
	return c.app()
}

func (c postsAdminController) pool() *gorm.DB {
	app := c.application()
	if app == nil {
		return nil
	}
	gdb, ok := app.Lookup[*gorm.DB]()
	if !ok {
		return nil
	}
	return gdb
}

func (c postsAdminController) db(ctx context.Context) *gorm.DB {
	if tx, ok := cabana.TxFromContext(ctx); ok {
		return tx
	}
	return c.pool()
}

func (postsAdminController) ListExtendQuery(ctx context.Context, db *gorm.DB) *gorm.DB {
	return restrictToOwnPosts(ctx, db)
}

func (postsAdminController) FormExtendQuery(ctx context.Context, db *gorm.DB) *gorm.DB {
	return restrictToOwnPosts(ctx, db)
}

func restrictToOwnPosts(ctx context.Context, db *gorm.DB) *gorm.DB {
	if db == nil {
		return db
	}
	principal, ok := bouncer.User(ctx)
	if !ok || principal == nil || !principal.Backend {
		return db.Where("1 = 0")
	}
	if cabana.Allows(principal, []string{PermissionAccessOtherPosts}) {
		return db
	}
	return db.Where("user_id = ?", principal.ID)
}

func (postsAdminController) ListRowStates(_ context.Context, _ *gorm.DB, records []any) ([][]pact.RowState, error) {
	out := make([][]pact.RowState, len(records))
	for i, record := range records {
		post, ok := record.(*models.Post)
		if !ok || post == nil {
			return nil, errors.New("posts admin: list record is not a post")
		}
		if !post.Published {
			out[i] = append(out[i], pact.RowStateDisabled)
		}
	}
	return out, nil
}

func (c postsAdminController) FilterOptions(scope string) []pact.Option {
	if scope != models.FilterCategories {
		return nil
	}
	db := c.pool()
	if db == nil {
		return nil
	}
	var cats []models.Category
	if err := db.Session(&gorm.Session{NewDB: true}).Order("name ASC, id ASC").Find(&cats).Error; err != nil {
		return nil
	}
	out := make([]pact.Option, 0, len(cats))
	for _, cat := range cats {
		out = append(out, pact.Option{Value: strconv.FormatUint(uint64(cat.ID), 10), Label: cat.Name})
	}
	return out
}

func (postsAdminController) AdminFieldRelations() []cabana.FieldRelationContract {
	return []cabana.FieldRelationContract{
		{
			Field:              "user",
			Kind:               "belongsTo",
			NewRelated:         func() any { return &cabana.BackendUser{} },
			ForeignKey:         "user_id",
			LabelColumn:        "login",
			WritableForeignKey: true,
		},
		{
			Field:             "categories",
			Kind:              "belongsToMany",
			NewRelated:        func() any { return &models.Category{} },
			NewPivot:          func() any { return &models.PostCategory{} },
			ParentForeignKey:  "post_id",
			RelatedForeignKey: "category_id",
			LabelColumn:       "name",
		},
		{
			Field:             "tags",
			Kind:              "belongsToMany",
			NewRelated:        func() any { return &models.Tag{} },
			NewPivot:          func() any { return &models.PostTag{} },
			ParentForeignKey:  "post_id",
			RelatedForeignKey: "tag_id",
			LabelColumn:       "name",
		},
	}
}

func (c postsAdminController) FormBeforeCreate(ctx context.Context, model any) error {
	post, ok := model.(*models.Post)
	if !ok || post == nil {
		return errors.New("posts admin: form model is not a post")
	}
	if post.UserID == nil || *post.UserID == 0 {
		principal, ok := bouncer.User(ctx)
		if ok && principal != nil && principal.Backend {
			id := principal.ID
			post.UserID = &id
		}
	}
	return preparePostWrite(ctx, post)
}

func (c postsAdminController) FormBeforeUpdate(ctx context.Context, model any) error {
	post, ok := model.(*models.Post)
	if !ok || post == nil {
		return errors.New("posts admin: form model is not a post")
	}
	if err := refuseOtherAuthor(ctx, post); err != nil {
		return err
	}
	return preparePostWrite(ctx, post)
}

func (c postsAdminController) FormBeforeDelete(ctx context.Context, model any) error {
	post, ok := model.(*models.Post)
	if !ok || post == nil {
		return errors.New("posts admin: form model is not a post")
	}
	return refuseOtherAuthor(ctx, post)
}

func refuseOtherAuthor(ctx context.Context, post *models.Post) error {
	principal, _ := bouncer.User(ctx)
	if post.CanEdit(principal) {
		return nil
	}
	return &cabana.ForbiddenError{Message: "golem15.journal::lang.journal.access_other_posts"}
}

func preparePostWrite(ctx context.Context, post *models.Post) error {
	if err := refuseUnpublishedWrite(ctx, post); err != nil {
		return err
	}
	if post.Published && post.PublishedAt == nil {
		return &cabana.ValidationError{Details: map[string]any{
			"published_at": []string{"golem15.journal::lang.post.published_validation"},
		}}
	}
	// D-02: the Blog Editor's Decode already stored the policy's output in
	// content; content_html gets the same HTML, without goldmark. Content the
	// save does not write (untouched, D-03) leaves content_html as it is.
	if writes, ok := cabana.FieldWritesFromContext(ctx); ok {
		for _, w := range writes["content"] {
			if !w.Default {
				continue
			}
			if html, isString := w.Value.(string); isString {
				post.ContentHTML = html
			}
		}
	}
	return nil
}

// FormAfterCreate writes content_html for every non-default locale whose
// content the save wrote (D-02).
func (c postsAdminController) FormAfterCreate(ctx context.Context, model any) error {
	return c.writeContentHTMLTranslations(ctx, model)
}

// FormAfterUpdate writes content_html for every non-default locale whose
// content the save wrote (D-02). Untouched locales are not listed and keep
// their content_html.
func (c postsAdminController) FormAfterUpdate(ctx context.Context, model any) error {
	return c.writeContentHTMLTranslations(ctx, model)
}

// writeContentHTMLTranslations stores each written non-default content
// value as that locale's content_html through the published
// cabana.TranslationWriter, inside the save transaction. Without a writer
// there is nothing to write.
func (c postsAdminController) writeContentHTMLTranslations(ctx context.Context, model any) error {
	post, ok := model.(*models.Post)
	if !ok || post == nil {
		return errors.New("posts admin: form model is not a post")
	}
	writes, ok := cabana.FieldWritesFromContext(ctx)
	if !ok {
		return nil
	}
	var pending []cabana.FieldWrite
	for _, w := range writes["content"] {
		if !w.Default && w.Locale != "" {
			pending = append(pending, w)
		}
	}
	if len(pending) == 0 {
		return nil
	}
	app := c.application()
	if app == nil {
		return nil
	}
	writer, ok := app.Lookup[cabana.TranslationWriter]()
	if !ok || writer == nil {
		return nil
	}
	tx := c.db(ctx)
	for _, w := range pending {
		html, isString := w.Value.(string)
		if !isString {
			return fmt.Errorf("posts admin: content for %s is %T, want a string", w.Locale, w.Value)
		}
		if err := writer.WriteTranslated(ctx, tx, post, "content_html", w.Locale, html); err != nil {
			return err
		}
	}
	return nil
}

func (c postsAdminController) AdminActions() []pact.AdminAction {
	return []pact.AdminAction{
		{
			Name:        "exportPosts",
			Label:       "golem15.journal::lang.posts.export_post",
			Permissions: []string{PermissionAccessImportExport},
			Run:         c.runExportPosts,
		},
		{
			Name:        "importPosts",
			Label:       "golem15.journal::lang.posts.import_post",
			Permissions: []string{PermissionAccessImportExport},
			Run:         c.runImportPosts,
		},
	}
}

func (c postsAdminController) runExportPosts(ctx context.Context, in pact.AdminActionInput) (pact.AdminActionResult, error) {
	path, dry, _ := console.IOPayloadPath(in.Payload, "journal-export")
	n, attachments, err := console.ExportToDir(ctx, c.db(ctx), path, dry, nil)
	if err != nil {
		return pact.AdminActionResult{}, err
	}
	msg := fmt.Sprintf("Exported %d posts to: %s", n, path)
	if dry {
		msg = fmt.Sprintf("Would export %d posts to: %s", n, path)
	}
	if attachments {
		msg += " File attachments are not included."
	}
	return pact.AdminActionResult{
		Message: msg,
		Data:    map[string]any{"count": n, "path": path, "dry_run": dry},
	}, nil
}

func (c postsAdminController) runImportPosts(ctx context.Context, in pact.AdminActionInput) (pact.AdminActionResult, error) {
	path, dry, force := console.IOPayloadPath(in.Payload, "journal-export")
	stats, err := console.ImportFromDir(ctx, c.db(ctx), path, force, dry, nil, func(post *models.Post) error {
		return refuseUnpublishedWrite(ctx, post)
	})
	if err != nil {
		return pact.AdminActionResult{}, err
	}
	msg := fmt.Sprintf("Results: %d created, %d updated, %d skipped, %d failed",
		stats.Created, stats.Updated, stats.Skipped, stats.Failed)
	if dry {
		msg = "Dry run complete (no changes made). " + msg
	}
	return pact.AdminActionResult{
		Message: msg,
		Data: map[string]any{
			"created": stats.Created,
			"updated": stats.Updated,
			"skipped": stats.Skipped,
			"failed":  stats.Failed,
			"path":    path,
			"dry_run": dry,
			"force":   force,
		},
	}, nil
}

func refuseUnpublishedWrite(ctx context.Context, post *models.Post) error {
	if !post.Published && post.PublishedAt == nil {
		return nil
	}
	principal, _ := bouncer.User(ctx)
	if cabana.Allows(principal, []string{PermissionAccessPublish}) {
		return nil
	}
	return &cabana.ForbiddenError{Message: "golem15.journal::lang.journal.access_publish"}
}