package api

import (
	"context"
	"net/http"
	"strings"
	"time"

	"git.golem15.com/golem15/sm-sitemap-plugin/classes"
	"git.golem15.com/golem15/sm-sitemap-plugin/models"
	"git.golem15.com/golem15/summercms/modules/backpack"
	"git.golem15.com/golem15/summercms/modules/lagoon"
	"git.golem15.com/golem15/summercms/modules/phrasebook"
	"git.golem15.com/golem15/summercms/modules/signpost"
	"gorm.io/gorm"
)

// errUnknownType is the refusal of a types entry for a key no content type
// has.
const errUnknownType = "golem15.sitemap::lang.errors.type_unknown"

// TypeInput is the settings of one content type in UpdateSettingsInput:
// only the fields sent change.
type TypeInput struct {
	Include *bool             `json:"include,omitempty" jsonschema:"list the type's records in the sitemaps"`
	Slug    *string           `json:"slug,omitempty" jsonschema:"the file name part of the type's files (sitemap-<slug>-<n>.xml): lowercase letters, digits and hyphens; empty for the default"`
	Titles  map[string]string `json:"titles,omitempty" jsonschema:"the type's heading in the HTML sitemap per locale"`
}

// UpdateSettingsInput is the body of PUT /_sitemap/api/v1/settings: only
// the fields sent change, with the checks of the settings screen.
type UpdateSettingsInput struct {
	SiteURL         *string              `json:"site_url,omitempty" jsonschema:"the public site address every sitemap address starts with, e.g. https://www.example.com; empty for the config value"`
	FileSize        *int                 `json:"file_size,omitempty" jsonschema:"addresses per sitemap file, 1 to 50000; a change renumbers every file"`
	ExtraURLs       *[]models.ExtraURL   `json:"extra_urls,omitempty" jsonschema:"the additional addresses (url: a path or an absolute URL on the site; lastmod: optional YYYY-MM-DD); replaces the list"`
	ImagesEnabled   *bool                `json:"images_enabled,omitempty" jsonschema:"list the pages' images in the sitemap-images files"`
	NewsEnabled     *bool                `json:"news_enabled,omitempty" jsonschema:"serve the Google News sitemap sitemap-news.xml (only for sites accepted in Google News)"`
	NewsPublication *string              `json:"news_publication,omitempty" jsonschema:"the publication name as registered in Google News; empty for the site name"`
	NewsSources     *[]string            `json:"news_sources,omitempty" jsonschema:"the article types and categories of the News sitemap, values of news_source_options (type:<key> or category:<key>:<id>); empty for every article type"`
	IndexNowEnabled *bool                `json:"indexnow_enabled,omitempty" jsonschema:"notify IndexNow engines of new, changed and removed addresses after each rebuild (production only); turning it on generates the key"`
	IndexNowNewKey  *bool                `json:"indexnow_new_key,omitempty" jsonschema:"generate a new IndexNow key; the old key file stops working at once"`
	HTMLEnabled     *bool                `json:"html_enabled,omitempty" jsonschema:"serve the HTML sitemap's data to the site"`
	HTMLPaths       map[string]string    `json:"html_paths,omitempty" jsonschema:"the site's HTML sitemap address per locale, e.g. {\"pl\":\"/mapa-strony\"}; a blank value removes the locale"`
	HTMLPageSize    *int                 `json:"html_page_size,omitempty" jsonschema:"links per HTML sitemap page, 50 to 500"`
	Types           map[string]TypeInput `json:"types,omitempty" jsonschema:"content type settings by type key"`
}

// settingsValues is the settings part of an answer.
func settingsValues(s models.Settings) map[string]any {
	return map[string]any{
		"site_url":         models.Text(s.SiteURL),
		"file_size":        s.EffectiveFileSize(),
		"default_locale":   models.Text(s.DefaultLocale),
		"extra_urls":       nonNil(s.Extra()),
		"images_enabled":   s.ImagesEnabled,
		"news_enabled":     s.NewsEnabled,
		"news_publication": models.Text(s.NewsPublication),
		"news_sources":     nonNil(s.Sources()),
		"indexnow_enabled": s.IndexNowEnabled,
		"html_enabled":     s.HTMLEnabled,
		"html_paths":       s.EffectiveHTMLPaths(),
		"html_page_size":   s.EffectiveHTMLPageSize(),
	}
}

func nonNil[T any](s []T) []T {
	if s == nil {
		return []T{}
	}
	return s
}

// fileJSON is one file in an answer, with its public address.
type fileJSON struct {
	Name    string     `json:"name"`
	URL     string     `json:"url"`
	Count   int        `json:"count"`
	LastMod *time.Time `json:"lastmod"`
}

// settingsBody is the answer of the settings routes: the settings, the
// content types (label and settings by key), the files of the index, the
// addresses left out by reason, the rebuild state, the IndexNow state and
// the values news_sources takes.
func settingsBody(ctx context.Context, app *backpack.App, db *gorm.DB) (map[string]any, error) {
	s, err := classes.LoadSettings(db)
	if err != nil {
		return nil, err
	}
	site := classes.SiteURL(app, s)
	reg, _ := app.Lookup[*signpost.Registry]()
	tr, _ := app.Lookup[*phrasebook.Translator]()
	types := map[string]any{}
	if reg != nil {
		rows, err := classes.LoadTypeSettings(db)
		if err != nil {
			return nil, err
		}
		for _, typ := range reg.ContentTypes() {
			cfg := classes.EffectiveType(typ, rows)
			label := typ.Label
			if tr != nil {
				label = tr.Get(ctx, typ.Label, nil)
			}
			titles := cfg.Titles
			if titles == nil {
				titles = map[string]string{}
			}
			types[typ.Key] = map[string]any{"label": label, "include": cfg.Include, "slug": cfg.Slug, "titles": titles}
		}
	}
	list, err := classes.SitemapFiles(db, app, s, time.Now().UTC())
	if err != nil {
		return nil, err
	}
	files := make([]fileJSON, 0, len(list))
	for _, f := range list {
		files = append(files, fileJSON{Name: f.Name, URL: site + "/" + f.Name, Count: f.Count, LastMod: f.LastMod})
	}
	leftOut, err := classes.LeftOut(db)
	if err != nil {
		return nil, err
	}
	sources, err := classes.NewsSources(db, reg, models.Text(s.DefaultLocale))
	if err != nil {
		return nil, err
	}
	index := ""
	if site != "" {
		index = site + "/sitemap.xml"
	}
	return map[string]any{
		"settings":            settingsValues(s),
		"types":               types,
		"index_url":           index,
		"files":               files,
		"left_out":            leftOut,
		"built_at":            s.BuiltAt,
		"building":            classes.Building(s.RebuildRequestedAt, s.BuiltAt, time.Now()),
		"indexnow":            classes.LoadIndexNowStatus(db, app, s),
		"news_source_options": sources,
	}, nil
}

// database returns the application's database bound to ctx.
func database(ctx context.Context, app *backpack.App) (*gorm.DB, error) {
	db, ok := app.Lookup[*gorm.DB]()
	if !ok || db == nil {
		return nil, classes.ErrNoDatabase
	}
	return db.WithContext(ctx), nil
}

// ShowSettings serves GET /_sitemap/api/v1/settings: the sitemap settings,
// the content types, the files with their address counts, the left-out
// counts, the IndexNow key and last notification (settingsBody).
func ShowSettings(app func() *backpack.App) http.HandlerFunc {
	return manage(app, func(ctx context.Context, a *backpack.App, _ *http.Request) (int, any, error) {
		db, err := database(ctx, a)
		if err != nil {
			return 0, nil, err
		}
		body, err := settingsBody(ctx, a, db)
		if err != nil {
			return 0, nil, err
		}
		return http.StatusOK, map[string]any{"data": body}, nil
	})
}

// UpdateSettings serves PUT /_sitemap/api/v1/settings: the fields sent
// change with the checks of the settings screen (422 validation_failed
// names the refused fields, types.<key>.<field> for a content type), the
// IndexNow key is generated as on the screen and a rebuild is queued once
// the change commits. It answers like ShowSettings.
func UpdateSettings(app func() *backpack.App) http.HandlerFunc {
	return manage(app, func(ctx context.Context, a *backpack.App, r *http.Request) (int, any, error) {
		var in UpdateSettingsInput
		if err := decode(r, &in); err != nil {
			return 0, nil, err
		}
		gdb, err := database(ctx, a)
		if err != nil {
			return 0, nil, err
		}
		err = lagoon.Transaction(ctx, gdb, func(ctx context.Context, tx *gorm.DB) error {
			return applySettings(ctx, a, tx, in)
		})
		if err != nil {
			return 0, nil, err
		}
		body, err := settingsBody(ctx, a, gdb)
		if err != nil {
			return 0, nil, err
		}
		return http.StatusOK, map[string]any{"data": body}, nil
	})
}

// applySettings writes in inside tx: the settings columns sent, the HTML
// sitemap addresses merged per locale, the content types, the IndexNow
// key, then queues a rebuild after the commit.
func applySettings(ctx context.Context, app *backpack.App, tx *gorm.DB, in UpdateSettingsInput) error {
	if err := tx.Exec(`INSERT INTO golem15_sitemap_settings (id) VALUES (1) ON CONFLICT (id) DO NOTHING`).Error; err != nil {
		return err
	}
	if err := tx.Exec(`SELECT id FROM golem15_sitemap_settings WHERE id = 1 FOR UPDATE`).Error; err != nil {
		return err
	}
	s, err := classes.LoadSettings(tx)
	if err != nil {
		return err
	}
	columns := map[string]any{}
	if in.SiteURL != nil {
		v := strings.TrimSpace(*in.SiteURL)
		s.SiteURL = &v
		columns["site_url"] = v
	}
	if in.FileSize != nil {
		s.FileSize = *in.FileSize
		columns["file_size"] = *in.FileSize
	}
	if in.ExtraURLs != nil {
		s.ExtraURLs = lagoon.Jsonable[[]models.ExtraURL]{Data: nonNil(*in.ExtraURLs), Valid: true}
		columns["extra_urls"] = s.ExtraURLs
	}
	if in.ImagesEnabled != nil {
		s.ImagesEnabled = *in.ImagesEnabled
		columns["images_enabled"] = *in.ImagesEnabled
	}
	if in.NewsEnabled != nil {
		s.NewsEnabled = *in.NewsEnabled
		columns["news_enabled"] = *in.NewsEnabled
	}
	if in.NewsPublication != nil {
		v := strings.TrimSpace(*in.NewsPublication)
		s.NewsPublication = &v
		columns["news_publication"] = v
	}
	if in.NewsSources != nil {
		list := []string{}
		for _, v := range *in.NewsSources {
			if v = strings.TrimSpace(v); v != "" {
				list = append(list, v)
			}
		}
		s.NewsSources = lagoon.Jsonable[[]string]{Data: list, Valid: true}
		columns["news_sources"] = s.NewsSources
	}
	if in.IndexNowEnabled != nil {
		s.IndexNowEnabled = *in.IndexNowEnabled
		columns["indexnow_enabled"] = *in.IndexNowEnabled
	}
	if in.HTMLEnabled != nil {
		s.HTMLEnabled = *in.HTMLEnabled
		columns["html_enabled"] = *in.HTMLEnabled
	}
	if in.HTMLPageSize != nil {
		s.HTMLPageSize = *in.HTMLPageSize
		columns["html_page_size"] = *in.HTMLPageSize
	}
	problems := s.Problems()
	delete(problems, "html_path")
	var paths map[string]string
	if in.HTMLPaths != nil {
		merged, bad := classes.MergeHTMLPaths(tx, in.HTMLPaths)
		if bad {
			problems["html_paths"] = []string{models.HTMLPathProblem}
		}
		paths = merged
	}
	var reg *signpost.Registry
	if app != nil {
		reg, _ = app.Lookup[*signpost.Registry]()
	}
	values, names := map[string]any{}, map[string]string{}
	for key, t := range in.Types {
		if reg == nil {
			problems["types."+key] = []string{errUnknownType}
			continue
		}
		if _, ok := reg.ContentType(key); !ok {
			problems["types."+key] = []string{errUnknownType}
			continue
		}
		base := classes.TypeFieldBase(key)
		names[base+"include"], names[base+"slug"], names[base+"title"] = "types."+key+".include", "types."+key+".slug", "types."+key+".titles"
		if t.Include != nil {
			values[base+"include"] = *t.Include
		}
		if t.Slug != nil {
			values[base+"slug"] = *t.Slug
		}
		if t.Titles != nil {
			values[base+"title"] = t.Titles
		}
	}
	if len(problems) > 0 {
		return &ProblemsError{Problems: problems}
	}
	if len(columns) > 0 {
		if err := tx.Model(&models.Settings{}).Where("id = ?", 1).Updates(columns).Error; err != nil {
			return err
		}
	}
	if paths != nil {
		if err := classes.StoreHTMLPaths(tx, paths); err != nil {
			return err
		}
	}
	if reg != nil && len(values) > 0 {
		refusals, err := classes.SaveTypeSettings(tx, reg.ContentTypes(), values)
		if err != nil {
			return err
		}
		if len(refusals) > 0 {
			out := map[string][]string{}
			for field, keys := range refusals {
				if name, ok := names[field]; ok {
					field = name
				}
				out[field] = keys
			}
			return &ProblemsError{Problems: out}
		}
	}
	if _, err := classes.EnsureKey(tx, s.IndexNowEnabled, in.IndexNowNewKey != nil && *in.IndexNowNewKey); err != nil {
		return err
	}
	return classes.RequestRebuild(ctx, app, tx)
}

// Rebuild serves POST /_sitemap/api/v1/rebuild: it queues a rebuild of the
// sitemap files now (the settings screen then shows files.building) and
// answers 202 {"data":{"queued":true}}.
func Rebuild(app func() *backpack.App) http.HandlerFunc {
	return manage(app, func(ctx context.Context, a *backpack.App, _ *http.Request) (int, any, error) {
		gdb, err := database(ctx, a)
		if err != nil {
			return 0, nil, err
		}
		if err := lagoon.Transaction(ctx, gdb, func(ctx context.Context, tx *gorm.DB) error {
			return classes.RequestRebuild(ctx, a, tx)
		}); err != nil {
			return 0, nil, err
		}
		return http.StatusAccepted, map[string]any{"data": map[string]any{"queued": true}}, nil
	})
}