package main

import (
	"fmt"
	"os"
	"strings"

	"github.com/gofiber/fiber/v2"
	"github.com/gofiber/fiber/v2/middleware/logger"
	"maunium.net/go/mautrix"
	"maunium.net/go/mautrix/id"
)

var (
	matrixClient *mautrix.Client
	defaultRoom  *string
	port         = "3000"
)

func init() {
	homeserverURL, ok := os.LookupEnv("HOMESERVER_URL")
	if !ok {
		panic("HOMESERVER_URL env var required")
	}
	userID, ok := os.LookupEnv("USER_ID")
	if !ok {
		panic("USER_ID env var required")
	} else {
		userID = strings.Replace(userID, homeserverURL, "", -1)
		userID = strings.TrimPrefix(userID, "@")
	}
	accessToken, ok := os.LookupEnv("ACCESS_TOKEN")
	if !ok {
		panic("ACCESS_TOKEN env var required")
	}

	if p, ok := os.LookupEnv("PORT"); ok {
		port = p
	}

	room, ok := os.LookupEnv("DEFAULT_ROOM")
	if ok {
		defaultRoom = &room
	}

	client, err := mautrix.NewClient(homeserverURL, id.NewUserID(userID, homeserverURL), accessToken)
	if err != nil {
		panic(err)
	}
	matrixClient = client
}

func main() {
	app := fiber.New()
	app.Use(logger.New())
	app.Post("/", HandlePayloadPost)
	app.Post("/alertmanager", HandleAlertmanagerPayloadPost)
	app.Listen(fmt.Sprintf(":%s", port))
}

func getRoom(roomID string) string {
	room := parseRoom(roomID)
	if strings.HasPrefix(room, "#") || !strings.HasPrefix("!", room) {
		if !strings.HasPrefix(room, "#") {
			room = fmt.Sprintf("#%s", room)
		}

		resp, err := matrixClient.ResolveAlias(id.RoomAlias(room))
		if err == nil {
			room = resp.RoomID.String()
		} else {
			room = strings.Replace(room, "#", "!", 1)
		}
	}

	return room
}

func parseRoom(room string) string {
	prefix := ""
	local := ""
	domain := ""

	parts := strings.Split(room, ":")
	if len(parts) == 2 {
		domain = parts[1]
	} else {
		domain = matrixClient.HomeserverURL.Host
	}

	if strings.HasPrefix(parts[0], "!") {
		prefix = "!"
		parts[0] = strings.TrimPrefix(parts[0], "!")
	}
	if strings.HasPrefix(parts[0], "#") {
		prefix = "#"
		parts[0] = strings.TrimPrefix(parts[0], "#")
	}

	local = parts[0]

	return fmt.Sprintf("%s%s:%s", prefix, local, domain)
}

func HandlePayloadPost(c *fiber.Ctx) error {
	payload := Payload{}

	if err := c.BodyParser(&payload); err != nil {
		return err
	}
	if err := payload.Validate(defaultRoom); err != nil {
		fmt.Println("Invalid payload - ", err)
		return c.Status(fiber.StatusBadRequest).SendString(err.Error())
	}

	switch payload.Type {
	case PayloadTypeText:
		_, err := matrixClient.SendText(id.RoomID(payload.RoomID), payload.Message)
		if err != nil {
			if httpErr, ok := err.(mautrix.HTTPError); ok {
				return c.Status(httpErr.Response.StatusCode).SendString(httpErr.RespError.Err)
			}
			return fiber.ErrInternalServerError
		}
	case PayloadTypeNotice:
		_, err := matrixClient.SendNotice(id.RoomID(payload.RoomID), payload.Message)
		if err != nil {
			if httpErr, ok := err.(mautrix.HTTPError); ok {
				return c.Status(httpErr.Response.StatusCode).SendString(httpErr.RespError.Err)
			}
			return fiber.ErrInternalServerError
		}
	}

	return c.SendStatus(fiber.StatusOK)
}