// Package api holds the golem15.feedback HTTP handlers: the public widget
// routes (config and submit) and the JWT preference route.
package api

import (
	"crypto/subtle"
	"io"
	"log/slog"
	"net/http"

	"git.golem15.com/golem15/sm-feedback-plugin/classes"
	"git.golem15.com/golem15/sm-feedback-plugin/models"
	"git.golem15.com/golem15/summercms/modules/backpack"
	"git.golem15.com/golem15/summercms/modules/lagoon"
	"git.golem15.com/golem15/summercms/modules/phrasebook"
	"gocloud.dev/blob"
	"gorm.io/gorm"
)

// configBody is FeedbackApiController::config's answer, in PHP's key order.
type configBody struct {
	Success bool       `json:"success"`
	Data    configData `json:"data"`
}

type configData struct {
	Position  *string       `json:"position"`
	AllowHide bool          `json:"allowHide"`
	Colors    configColors  `json:"colors"`
	Labels    models.Labels `json:"labels"`
}

type configColors struct {
	Primary *string `json:"primary"`
	Accent  *string `json:"accent"`
}

// Config handles GET /_feedback/api/v1/{key}/config: the widget's position,
// colors and labels (English for ?lang=en, Polish otherwise) once the key
// and the Origin pass the widget gate.
func Config(app *backpack.App) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		settings, ok := gate(w, r, app)
		if !ok {
			return
		}
		writeJSON(w, http.StatusOK, configBody{
			Success: true,
			Data: configData{
				Position:  settings.Position,
				AllowHide: settings.AllowHide,
				Colors:    configColors{Primary: settings.ColorPrimary, Accent: settings.ColorAccent},
				Labels:    settings.LabelsForLocale(r.URL.Query().Get("lang")),
			},
		})
	}
}

// SubmitRules are FeedbackApiController::submit's validation rules.
var SubmitRules = []lagoon.RequestRule{
	{Field: "message", Rules: lagoon.ParseRules("required|string|max:5000")},
	{Field: "type", Rules: lagoon.ParseRules("required|in:bug,feature,other")},
	{Field: "email", Rules: lagoon.ParseRules("nullable|email|max:255")},
	{Field: "page_url", Rules: lagoon.ParseRules("required|string|max:2000")},
	{Field: "user_agent", Rules: lagoon.ParseRules("nullable|string|max:500")},
	{Field: "console_log", Rules: lagoon.ParseRules("nullable|string|max:20000")},
	{Field: "screenshot", Rules: lagoon.ParseRules("nullable|image|mimes:jpg,jpeg,png,gif,webp|max:10240")},
}

// validationBody is the widget routes' 422 envelope.
type validationBody struct {
	Error   bool   `json:"error"`
	Message string `json:"message"`
	Details any    `json:"details"`
}

// Submit handles POST /_feedback/api/v1/{key}/submit (multipart, from the
// widget): after the widget gate it validates the report as PHP does (422
// "Validation failed" with Laravel's errors under details), refuses a
// screenshot whose bytes are not an image, stores the submission with its
// public screenshot and queues the G15Office job in one transaction, and
// answers 202 {"success":true}. The visitor never waits on G15Office.
func Submit(app *backpack.App) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		if _, ok := gate(w, r, app); !ok {
			return
		}
		input, ok := readInput(w, r)
		if !ok {
			return
		}
		ctx := r.Context()
		gdb := database(app)
		tr, _ := app.Lookup[*phrasebook.Translator]()
		errs, err := lagoon.ValidateRequest(ctx, gdb.WithContext(ctx), input, SubmitRules, tr)
		if err != nil {
			writeOpaque500(w)
			return
		}
		if len(errs) > 0 {
			writeJSON(w, http.StatusUnprocessableEntity, validationBody{
				Error: true, Message: "Validation failed",
				Details: orderedErrors{errs: errs, order: lagoon.ErrorKeys(errs, SubmitRules)},
			})
			return
		}
		var shot *classes.Screenshot
		if upload, isFile := input["screenshot"].(lagoon.UploadedFile); isFile && upload.Open != nil {
			data, err := readUpload(upload)
			if err != nil {
				writeOpaque500(w)
				return
			}
			if !classes.IsAllowedImage(data) {
				writeJSON(w, http.StatusUnprocessableEntity, validationBody{
					Error: true, Message: "Validation failed",
					Details: map[string][]string{"screenshot": {"The file is not a valid image."}},
				})
				return
			}
			shot = &classes.Screenshot{Filename: upload.Filename, Data: data}
		}
		var bucket *blob.Bucket
		if shot != nil {
			if bucket, ok = app.Lookup[*blob.Bucket](); !ok || bucket == nil {
				slog.Default().Error("golem15.feedback: upload bucket is not configured")
				writeOpaque500(w)
				return
			}
		}
		sub := &models.Submission{
			Message:    stringOr(inputString(input, "message")),
			Type:       stringOr(inputString(input, "type")),
			Email:      inputString(input, "email"),
			PageURL:    stringOr(inputString(input, "page_url")),
			UserAgent:  inputString(input, "user_agent"),
			ConsoleLog: inputString(input, "console_log"),
		}
		if err := classes.StoreSubmission(ctx, app, gdb, bucket, sub, shot); err != nil {
			slog.Default().Error("golem15.feedback: storing a submission failed", slog.Any("error", err))
			writeOpaque500(w)
			return
		}
		writeJSON(w, http.StatusAccepted, successBody{Success: true})
	}
}

type successBody struct {
	Success bool `json:"success"`
}

func stringOr(s *string) string {
	if s == nil {
		return ""
	}
	return *s
}

// readUpload reads an uploaded file; the max:10240 rule already bounded it.
func readUpload(upload lagoon.UploadedFile) ([]byte, error) {
	rc, err := upload.Open()
	if err != nil {
		return nil, err
	}
	defer rc.Close()
	return io.ReadAll(rc)
}

// gate loads the settings (creating them on first access) and runs the
// widget checks of both public routes in PHP's order: the key (404
// "Not found") then the Origin (403 "Origin not allowed").
func gate(w http.ResponseWriter, r *http.Request, app *backpack.App) (*models.Settings, bool) {
	gdb := database(app)
	if gdb == nil {
		writeOpaque500(w)
		return nil, false
	}
	settings, err := models.Instance(r.Context(), gdb)
	if err != nil {
		writeOpaque500(w)
		return nil, false
	}
	if !KeyMatches(settings, r.PathValue("key")) {
		writeError(w, http.StatusNotFound, "Not found")
		return nil, false
	}
	if !OriginAllowed(r.Header.Get("Origin"), settings) {
		writeError(w, http.StatusForbidden, "Origin not allowed")
		return nil, false
	}
	return settings, true
}

// KeyMatches is FeedbackApiController::keyMatches: the widget is enabled,
// has a key, and key equals it, compared in constant time (hash_equals).
func KeyMatches(settings *models.Settings, key string) bool {
	if settings == nil || !settings.Enabled || settings.WidgetKey == "" {
		return false
	}
	return subtle.ConstantTimeCompare([]byte(settings.WidgetKey), []byte(key)) == 1
}

// OriginAllowed is FeedbackApiController::isOriginAllowed. No Origin (curl,
// a server, a same-origin request) passes. An Origin passes only when its
// URL host, lower-cased, is on the settings' allowed-origins list; an
// Origin without a host fails, and an empty list fails every Origin, so a
// widget that was never configured cannot be embedded anywhere.
func OriginAllowed(origin string, settings *models.Settings) bool {
	if origin == "" {
		return true
	}
	host, ok := models.URLHost(origin)
	if !ok || host == "" {
		return false
	}
	allowed := settings.AllowedOriginHosts()
	if len(allowed) == 0 {
		return false
	}
	host = models.ASCIILower(host)
	for _, a := range allowed {
		if a == host {
			return true
		}
	}
	return false
}

func database(app *backpack.App) *gorm.DB {
	if app == nil {
		return nil
	}
	gdb, ok := app.Lookup[*gorm.DB]()
	if !ok || gdb == nil {
		return nil
	}
	return gdb
}