package handlers

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"

	"github.com/labstack/echo/v5"
	"trankilou.fr/lassistanoque/backend/internal/domain"
	"trankilou.fr/lassistanoque/backend/internal/service/auth"
)

func NewAuthGroup(prefix string, e *echo.Group, service *auth.Service) *echo.Group {
	authHandler := &AuthHandler{
		authService: service,
	}
	auth := e.Group(prefix)
	auth.POST("/login", authHandler.Login)
	auth.GET("/oidc/providers", authHandler.OIDCProviders)
	auth.GET("/oidc/login", authHandler.OIDCLogin)
	auth.GET("/oidc/callback", authHandler.OIDCCallback)
	auth.POST("/register", authHandler.Register)
	return auth
}

type AuthHandler struct {
	authService *auth.Service
}

type loginRequest struct {
	Email    string `json:"email" validate:"required,email"`
	Password string `json:"password" validate:"required"`
}

type loginResponse struct {
	AccessToken  string       `json:"accessToken"`
	RefreshToken string       `json:"refreshToken"`
	ExpiresAt    string       `json:"expiresAt"`
	User         *domain.User `json:"user"`
}

func (h AuthHandler) Login(c *echo.Context) error {
	var req loginRequest
	if err := c.Bind(&req); err != nil {
		return echo.NewHTTPError(http.StatusBadRequest, "invalid request")
	}
	if req.Email == "" || req.Password == "" {
		return echo.NewHTTPError(http.StatusBadRequest, "email and password are required")
	}

	creds := auth.Credentials{
		Method:   "password",
		Email:    req.Email,
		Password: req.Password,
	}

	session, err := h.authService.Login(context.Background(), creds)
	if err != nil {
		c.Logger().Error(fmt.Sprintf("error while login: %s", err))
		return echo.NewHTTPError(http.StatusUnauthorized, "login error")
	}

	resp := loginResponse{
		AccessToken:  session.AccessToken,
		RefreshToken: session.RefreshToken,
		ExpiresAt:    session.ExpiresAt.Format("2006-01-02T15:04:05Z07:00"),
	}
	resp.User = session.User

	return c.JSON(http.StatusOK, resp)
}

// oidcRedirectURI reconstruit l'URL de callback du serveur à partir de la
// requête. Elle doit être identique entre /oidc/login et /oidc/callback.
func oidcRedirectURI(c *echo.Context) string {
	scheme := "http"
	if proto := c.Request().Header.Get("X-Forwarded-Proto"); proto != "" {
		scheme = proto
	} else if c.Request().TLS != nil {
		scheme = "https"
	}
	host := c.Request().Header.Get("X-Forwarded-Host")
	if host == "" {
		host = c.Request().Host
	}
	return scheme + "://" + host + "/api/auth/oidc/callback"
}

func (h AuthHandler) OIDCProviders(c *echo.Context) error {
	providers, err := h.authService.ListOIDCProviders()
	if err != nil {
		c.Logger().Error(fmt.Sprintf("error listing oidc providers: %s", err))
		return echo.NewHTTPError(http.StatusInternalServerError, "error listing oidc providers")
	}
	return c.JSON(http.StatusOK, providers)
}

func (h AuthHandler) OIDCLogin(c *echo.Context) error {
	providerID := c.QueryParam("provider")
	if providerID == "" {
		return echo.NewHTTPError(http.StatusBadRequest, "provider query parameter is required")
	}

	authorizeURL, err := h.authService.OIDCAuthorizeURL(context.Background(), providerID, oidcRedirectURI(c))
	if err != nil {
		c.Logger().Error(fmt.Sprintf("error building oidc authorize url: %s", err))
		return c.Redirect(http.StatusFound, "/login?error=oidc")
	}
	return c.Redirect(http.StatusFound, authorizeURL)
}

func (h AuthHandler) OIDCCallback(c *echo.Context) error {
	if errParam := c.QueryParam("error"); errParam != "" {
		c.Logger().Error(fmt.Sprintf("oidc provider returned an error: %s", errParam))
		return c.Redirect(http.StatusFound, "/login?error=oidc")
	}
	code := c.QueryParam("code")
	state := c.QueryParam("state")
	if code == "" || state == "" {
		return echo.NewHTTPError(http.StatusBadRequest, "code and state are required")
	}

	session, err := h.authService.OIDCCallback(context.Background(), state, code, oidcRedirectURI(c))
	if err != nil {
		c.Logger().Error(fmt.Sprintf("error while oidc callback: %s", err))
		return c.Redirect(http.StatusFound, "/login?error=oidc")
	}

	// L'application SPA est servie par ce même serveur (même origine) et lit
	// ses tokens dans localStorage: on les dépose ici puis on redirige vers
	// l'application, sans jamais les faire transiter dans une URL.
	page := fmt.Sprintf(`<!doctype html>
<html>
<head><meta charset="utf-8"><title>Connexion en cours...</title></head>
<body>
<script>
localStorage.setItem("accessToken", %q);
localStorage.setItem("refreshToken", %q);
location.replace("/");
</script>
</body>
</html>`, session.AccessToken, session.RefreshToken)
	return c.Blob(http.StatusOK, "text/html; charset=utf-8", []byte(page))
}

func (h AuthHandler) Register(c *echo.Context) error {

	reader := c.Request().Body
	var registration auth.Registration
	decoder := json.NewDecoder(reader)
	err := decoder.Decode(&registration)
	if err != nil {
		return c.String(http.StatusBadRequest, "malformatted registration")
	}

	user, err := h.authService.Register(registration)
	if err != nil {
		return c.String(http.StatusBadRequest, err.Error())
	}
	return c.JSON(http.StatusCreated, user)
}