package server

import (
	"errors"
	"log/slog"
	"net/http"

	"github.com/go-chi/chi/v5"

	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/auth"
	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/dinners"
)

// maxDinnerBody bounds a POST or PATCH /dinners request body.
const maxDinnerBody = 16 << 10

// dinnerCreate is the POST /dinners body: a name or a recipe_url.
type dinnerCreate struct {
	Name      *string `json:"name"`
	RecipeURL *string `json:"recipe_url"`
}

// dinnerPatch is the PATCH /dinners/{id} body. Every field is optional;
// unknown fields and null values are refused.
type dinnerPatch struct {
	Name         *string `json:"name"`
	Method       *string `json:"method"`
	MinutesTotal *int    `json:"minutes_total"`
	Difficulty   *string `json:"difficulty"`
}

type dinnerList struct {
	Dinners []dinners.Dinner `json:"dinners"`
}

// getDinners answers GET /dinners?status=regular|quest_log.
func getDinners(logger *slog.Logger, svc *dinners.Service) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		list, err := svc.List(r.Context(), r.URL.Query().Get("status"))
		if err != nil {
			writeDinnerError(w, r, logger, "list dinners", err)
			return
		}
		writeJSON(w, r, logger, http.StatusOK, dinnerList{Dinners: list})
	}
}

// postDinner adds a Regular, recording the session's actor as updated_by.
func postDinner(logger *slog.Logger, svc *dinners.Service) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		actor, ok := actorOrFail(w, r, logger)
		if !ok {
			return
		}
		body, err := decodePatch[dinnerCreate](http.MaxBytesReader(w, r.Body, maxDinnerBody))
		if err != nil {
			writeError(w, r, logger, http.StatusBadRequest, "invalid_request", err.Error())
			return
		}
		d, err := svc.CreateRegular(r.Context(), dinners.NewRegular(body), actor.Subject)
		if err != nil {
			writeDinnerError(w, r, logger, "create dinner", err)
			return
		}
		writeJSON(w, r, logger, http.StatusCreated, d)
	}
}

// patchDinner edits a dinner, recording the session's actor as updated_by.
func patchDinner(logger *slog.Logger, svc *dinners.Service) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		actor, ok := actorOrFail(w, r, logger)
		if !ok {
			return
		}
		patch, err := decodePatch[dinnerPatch](http.MaxBytesReader(w, r.Body, maxDinnerBody))
		if err != nil {
			writeError(w, r, logger, http.StatusBadRequest, "invalid_request", err.Error())
			return
		}
		d, err := svc.Update(r.Context(), chi.URLParam(r, "id"), dinners.Patch(patch), actor.Subject)
		if err != nil {
			writeDinnerError(w, r, logger, "update dinner", err)
			return
		}
		writeJSON(w, r, logger, http.StatusOK, d)
	}
}

// deleteDinner archives a dinner; the row is never deleted.
func deleteDinner(logger *slog.Logger, svc *dinners.Service) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		actor, ok := actorOrFail(w, r, logger)
		if !ok {
			return
		}
		d, err := svc.Archive(r.Context(), chi.URLParam(r, "id"), actor.Subject)
		if err != nil {
			writeDinnerError(w, r, logger, "archive dinner", err)
			return
		}
		writeJSON(w, r, logger, http.StatusOK, d)
	}
}

// postDinnerFavorite toggles a dinner's is_favorite.
func postDinnerFavorite(logger *slog.Logger, svc *dinners.Service) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		actor, ok := actorOrFail(w, r, logger)
		if !ok {
			return
		}
		d, err := svc.ToggleFavorite(r.Context(), chi.URLParam(r, "id"), actor.Subject)
		if err != nil {
			writeDinnerError(w, r, logger, "toggle dinner favorite", err)
			return
		}
		writeJSON(w, r, logger, http.StatusOK, d)
	}
}

// actorOrFail returns the session's actor, or answers 500 when the request
// has none, which behind requireSession is a wiring bug.
func actorOrFail(w http.ResponseWriter, r *http.Request, logger *slog.Logger) (auth.Actor, bool) {
	actor, ok := auth.ActorFrom(r.Context())
	if !ok {
		logger.ErrorContext(r.Context(), r.Method+" "+r.URL.Path+" without a session")
		writeError(w, r, logger, http.StatusInternalServerError, "internal", "internal error")
	}
	return actor, ok
}

// writeDinnerError maps a dinners.Service error to its API error.
func writeDinnerError(w http.ResponseWriter, r *http.Request, logger *slog.Logger, action string, err error) {
	var invalid *dinners.ValidationError
	var dup *dinners.DuplicateError
	switch {
	case errors.As(err, &invalid):
		writeError(w, r, logger, http.StatusBadRequest, "invalid_dinner", invalid.Error())
	case errors.As(err, &dup):
		writeError(w, r, logger, http.StatusConflict, "duplicate_dinner", dup.Error())
	case errors.Is(err, dinners.ErrNotFound):
		writeError(w, r, logger, http.StatusNotFound, "not_found", "dinner not found")
	default:
		logger.ErrorContext(r.Context(), action, "error", err)
		writeError(w, r, logger, http.StatusInternalServerError, "internal", "internal error")
	}
}