package api

import (
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"strconv"
	"strings"

	"gardomatic.kleiax.de/internal/platform/validate"
	"github.com/julienschmidt/httprouter"
)

func (app *application) readIDParam(r *http.Request) (int, error) {
	return app.readNamedIDParam(r, "id")
}

func (app *application) readNamedIDParam(r *http.Request, name string) (int, error) {
	params := httprouter.ParamsFromContext(r.Context())
	id, err := strconv.Atoi(params.ByName(name))
	if err != nil || id < 1 {
		return 0, errors.New("invalid id parameter")
	}

	return id, nil
}

func (app *application) readGardenIDParam(r *http.Request) (int, error) {
	params := httprouter.ParamsFromContext(r.Context())

	id, err := strconv.Atoi(params.ByName("gardenID"))
	if err != nil || id < 1 {
		return 0, errors.New("invalid garden id parameter")
	}

	return id, nil
}

type envelope map[string]any

func (app *application) writeJSON(w http.ResponseWriter, status int, data envelope, headers http.Header) error {
	js, err := json.MarshalIndent(data, "", "\t")
	if err != nil {
		return err
	}

	js = append(js, '\n')

	for key, values := range headers {
		for _, value := range values {
			w.Header().Add(key, value)
		}
	}

	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	w.Write(js)

	return nil
}

func (app *application) readJSON(w http.ResponseWriter, r *http.Request, dst any) error {
	r.Body = http.MaxBytesReader(w, r.Body, 2_097_152)

	dec := json.NewDecoder(r.Body)
	dec.DisallowUnknownFields()

	err := dec.Decode(dst)
	if err != nil {
		var syntaxError *json.SyntaxError
		var unmarshalTypeError *json.UnmarshalTypeError
		var invalidUnmarshalError *json.InvalidUnmarshalError
		var maxBytesError *http.MaxBytesError

		switch {
		case errors.As(err, &syntaxError):
			return fmt.Errorf("body contains badly-formed JSON (at character %d)", syntaxError.Offset)

		case errors.Is(err, io.ErrUnexpectedEOF):
			return errors.New("body contains badly-formed JSON")

		case errors.As(err, &unmarshalTypeError):
			if unmarshalTypeError.Field != "" {
				return fmt.Errorf("body contains incorrect JSON type for field %q", unmarshalTypeError.Field)
			}
			return fmt.Errorf("body contains incorrect JSON type (at character %d)", unmarshalTypeError.Offset)

		case errors.Is(err, io.EOF):
			return errors.New("body must not be empty")

		case strings.HasPrefix(err.Error(), "json: unknown field "):
			fieldName := strings.TrimPrefix(err.Error(), "json: unknown field ")
			return fmt.Errorf("body contains unknown key %s", fieldName)

		case errors.As(err, &maxBytesError):
			return fmt.Errorf("body must not be larger than %d bytes", maxBytesError.Limit)

		case errors.As(err, &invalidUnmarshalError):
			panic(err)

		default:
			return err
		}
	}

	err = dec.Decode(&struct{}{})
	if !errors.Is(err, io.EOF) {
		return errors.New("body must only contain a single JSON value")
	}

	return nil
}

func validateImageData(v *validate.Validator, imageData string) {
	if imageData == "" {
		return
	}
	v.Check(len(imageData) <= 1_500_000, "image_data", "must not be larger than 1.5 MB")
	v.Check(strings.HasPrefix(imageData, "data:image/jpeg;base64,") || strings.HasPrefix(imageData, "data:image/png;base64,") || strings.HasPrefix(imageData, "data:image/webp;base64,"), "image_data", "must be a JPEG, PNG or WebP image")
}

//lint:ignore U1000 retained for the upcoming list filters
func (app *application) readString(qs url.Values, key string, defaultValue string) string {
	s := qs.Get(key)

	if s == "" {
		return defaultValue
	}

	return s
}

//lint:ignore U1000 retained for the upcoming list filters
func (app *application) readCSV(qs url.Values, key string, defaultValue []string) []string {
	csv := qs.Get(key)

	if csv == "" {
		return defaultValue
	}

	return strings.Split(csv, ",")
}

//lint:ignore U1000 retained for the upcoming pagination support
func (app *application) readInt(qs url.Values, key string, defaultValue int, v *validate.Validator) int {
	s := qs.Get(key)

	if s == "" {
		return defaultValue
	}

	i, err := strconv.Atoi(s)
	if err != nil {
		v.AddError(key, "must be an integer value")
		return defaultValue
	}

	return i
}

func (app *application) background(fn func()) {
	app.wg.Go(func() {
		defer func() {
			pv := recover()
			if pv != nil {
				app.logger.Error(fmt.Sprintf("%v", pv))
			}
		}()

		fn()
	})
}