package handlers

import (
	"database/sql"
	"fmt"
	"strings"

	"github.com/a-h/templ"
	"github.com/go-playground/validator/v10"
	"github.com/labstack/echo/v4"

	"git.grosinger.net/tgrosinger/saasitone/pkg/context"
	"git.grosinger.net/tgrosinger/saasitone/pkg/form"
	"git.grosinger.net/tgrosinger/saasitone/pkg/log"
	"git.grosinger.net/tgrosinger/saasitone/pkg/middleware"
	"git.grosinger.net/tgrosinger/saasitone/pkg/models/sqlc"
	"git.grosinger.net/tgrosinger/saasitone/pkg/msg"
	"git.grosinger.net/tgrosinger/saasitone/pkg/page"
	"git.grosinger.net/tgrosinger/saasitone/pkg/redirect"
	"git.grosinger.net/tgrosinger/saasitone/pkg/services"
	"git.grosinger.net/tgrosinger/saasitone/templ/layouts"
	"git.grosinger.net/tgrosinger/saasitone/templ/pages"
	"git.grosinger.net/tgrosinger/saasitone/templates"
)

const (
	routeNameForgotPassword       = "forgot_password"
	routeNameForgotPasswordSubmit = "forgot_password.submit"
	routeNameLogin                = "login"
	routeNameLoginSubmit          = "login.submit"
	routeNameLogout               = "logout"
	routeNameRegister             = "register"
	routeNameRegisterSubmit       = "register.submit"
	routeNameResetPassword        = "reset_password"
	routeNameResetPasswordSubmit  = "reset_password.submit"
	routeNameVerifyEmail          = "verify_email"
)

type (
	Auth struct {
		auth *services.AuthClient
		mail *services.MailClient
		db   *services.DBClient
		*services.TemplateRenderer
	}
)

func init() {
	Register(new(Auth))
}

func (h *Auth) Init(c *services.Container) error {
	h.TemplateRenderer = c.TemplateRenderer
	h.db = c.DB
	h.auth = c.Auth
	h.mail = c.Mail
	return nil
}

func (h *Auth) Routes(g *echo.Group) {
	g.GET("/logout", h.Logout, middleware.RequireAuthentication()).Name = routeNameLogout
	g.GET("/email/verify/:token", h.VerifyEmail).Name = routeNameVerifyEmail

	noAuth := g.Group("/user", middleware.RequireNoAuthentication())
	noAuth.GET("/login", h.LoginPage).Name = routeNameLogin
	noAuth.POST("/login", h.LoginSubmit).Name = routeNameLoginSubmit
	noAuth.GET("/register", h.RegisterPage).Name = routeNameRegister
	noAuth.POST("/register", h.RegisterSubmit).Name = routeNameRegisterSubmit
	noAuth.GET("/password", h.ForgotPasswordPage).Name = routeNameForgotPassword
	noAuth.POST("/password", h.ForgotPasswordSubmit).Name = routeNameForgotPasswordSubmit

	resetGroup := noAuth.Group("/password/reset",
		middleware.LoadUser(h.db),
		middleware.LoadValidPasswordToken(h.auth),
	)
	resetGroup.GET("/token/:user/:password_token/:token", h.ResetPasswordPage).Name = routeNameResetPassword
	resetGroup.POST("/token/:user/:password_token/:token", h.ResetPasswordSubmit).Name = routeNameResetPasswordSubmit
}

func (h *Auth) ForgotPasswordPage(ctx echo.Context) error {
	p := page.New(ctx)
	p.Name = templates.PageForgotPassword
	p.Title = "Forgot password"

	f := form.Get[pages.ForgotPasswordForm](ctx)
	component := pages.ForgotPassword(p, f)

	// TODO: This can be reused
	p.LayoutComponent = func(content templ.Component) templ.Component {
		return layouts.Auth(p, content)
	}

	return h.RenderPageTempl(ctx, p, component)
}

func (h *Auth) ForgotPasswordSubmit(ctx echo.Context) error {
	var input pages.ForgotPasswordForm

	succeed := func() error {
		form.Clear(ctx)
		msg.Success(ctx, "An email containing a link to reset your password will be sent to this address if it exists in our system.")
		return h.ForgotPasswordPage(ctx)
	}

	err := form.Submit(ctx, &input)

	switch err.(type) {
	case nil:
	case validator.ValidationErrors:
		return h.ForgotPasswordPage(ctx)
	default:
		return err
	}

	// Attempt to load the user
	u, err := h.db.C.GetUserByEmail(ctx.Request().Context(), strings.ToLower(input.Email))
	if err == sql.ErrNoRows {
		return succeed()
	} else if err != nil {
		return fail(err, "error querying user during forgot password")
	}

	// Generate the token
	token, pt, err := h.auth.GeneratePasswordResetToken(ctx, u.ID)
	if err != nil {
		return fail(err, "error generating password reset token")
	}

	log.Ctx(ctx).Info("generated password reset token",
		"user_id", u.ID,
	)

	// Email the user
	url := ctx.Echo().Reverse(routeNameResetPassword, u.ID, pt.ID, token)
	err = h.mail.
		Compose().
		To(u.Email).
		Subject("Reset your password").
		Body(fmt.Sprintf("Go here to reset your password: %s", url)).
		Send(ctx)
	if err != nil {
		return fail(err, "error sending password reset email")
	}

	return succeed()
}

func (h *Auth) LoginPage(ctx echo.Context) error {
	p := page.New(ctx)
	p.Name = templates.PageLogin
	p.Title = "Log in"

	f := form.Get[pages.LoginForm](ctx)
	component := pages.Login(p, f)

	// TODO: This can be reused
	p.LayoutComponent = func(content templ.Component) templ.Component {
		return layouts.Auth(p, content)
	}

	return h.RenderPageTempl(ctx, p, component)
}

func (h *Auth) LoginSubmit(ctx echo.Context) error {
	var input pages.LoginForm

	authFailed := func() error {
		input.SetFieldError("Email", "")
		input.SetFieldError("Password", "")
		msg.Danger(ctx, "Invalid credentials. Please try again.")
		return h.LoginPage(ctx)
	}

	err := form.Submit(ctx, &input)

	switch err.(type) {
	case nil:
	case validator.ValidationErrors:
		return h.LoginPage(ctx)
	default:
		return err
	}

	// Attempt to load the user
	u, err := h.db.C.GetUserByEmail(ctx.Request().Context(), strings.ToLower(input.Email))
	if err == sql.ErrNoRows {
		return authFailed()
	} else if err != nil {
		return fail(err, "error querying user during login")
	}

	// Check if the password is correct
	err = h.auth.CheckPassword(input.Password, u.Password)
	if err != nil {
		return authFailed()
	}

	// Log the user in
	err = h.auth.Login(ctx, u.ID)
	if err != nil {
		return fail(err, "unable to log in user")
	}

	msg.Success(ctx, fmt.Sprintf("Welcome back, <strong>%s</strong>. You are now logged in.", u.Name))

	return redirect.New(ctx).
		Route(routeNameHome).
		Go()
}

func (h *Auth) Logout(ctx echo.Context) error {
	if err := h.auth.Logout(ctx); err == nil {
		msg.Success(ctx, "You have been logged out successfully.")
	} else {
		msg.Danger(ctx, "An error occurred. Please try again.")
	}
	return redirect.New(ctx).
		Route(routeNameHome).
		Go()
}

func (h *Auth) RegisterPage(ctx echo.Context) error {
	p := page.New(ctx)
	p.Name = templates.PageRegister
	p.Title = "Register"

	f := form.Get[pages.RegisterForm](ctx)
	component := pages.Register(p, f)

	// TODO: This can be reused
	p.LayoutComponent = func(content templ.Component) templ.Component {
		return layouts.Auth(p, content)
	}

	return h.RenderPageTempl(ctx, p, component)
}

func (h *Auth) RegisterSubmit(ctx echo.Context) error {
	var input pages.RegisterForm

	err := form.Submit(ctx, &input)

	switch err.(type) {
	case nil:
	case validator.ValidationErrors:
		return h.RegisterPage(ctx)
	default:
		return err
	}

	// Hash the password
	pwHash, err := h.auth.HashPassword(input.Password)
	if err != nil {
		return fail(err, "unable to hash password")
	}

	// Attempt creating the user
	u, err := h.db.C.CreateUser(ctx.Request().Context(), sqlc.CreateUserParams{
		Name:     input.Name,
		Email:    input.Email,
		Password: pwHash,
	})
	if err != nil {
		if strings.HasPrefix(err.Error(), "UNIQUE constraint failed") {
			msg.Warning(ctx, "A user with this email address already exists. Please log in.")
			return redirect.New(ctx).
				Route(routeNameLogin).
				Go()
		}

		return fail(err, "unable to create user")
	}

	log.Ctx(ctx).Info("user created",
		"user_name", u.Name,
		"user_id", u.ID,
	)

	// Log the user in
	err = h.auth.Login(ctx, u.ID)
	if err != nil {
		log.Ctx(ctx).Error("unable to log user in",
			"error", err,
			"user_id", u.ID,
		)
		msg.Info(ctx, "Your account has been created.")
		return redirect.New(ctx).
			Route(routeNameLogin).
			Go()
	}

	msg.Success(ctx, "Your account has been created. You are now logged in.")

	// Send the verification email
	h.sendVerificationEmail(ctx, u)

	return redirect.New(ctx).
		Route(routeNameHome).
		Go()
}

func (h *Auth) sendVerificationEmail(ctx echo.Context, usr sqlc.User) {
	// Generate a token
	token, err := h.auth.GenerateEmailVerificationToken(usr.Email)
	if err != nil {
		log.Ctx(ctx).Error("unable to generate email verification token",
			"user_id", usr.ID,
			"error", err,
		)
		return
	}

	// Send the email
	url := ctx.Echo().Reverse(routeNameVerifyEmail, token)
	err = h.mail.
		Compose().
		To(usr.Email).
		Subject("Confirm your email address").
		Body(fmt.Sprintf("Click here to confirm your email address: %s", url)).
		Send(ctx)
	if err != nil {
		log.Ctx(ctx).Error("unable to send email verification link",
			"user_id", usr.ID,
			"error", err,
		)
		return
	}

	msg.Info(ctx, "An email was sent to you to verify your email address.")
}

func (h *Auth) ResetPasswordPage(ctx echo.Context) error {
	p := page.New(ctx)
	p.Name = templates.PageResetPassword
	p.Title = "Reset password"

	f := form.Get[pages.ResetPasswordForm](ctx)
	component := pages.ResetPassword(p, f)

	// TODO: This can be reused
	p.LayoutComponent = func(content templ.Component) templ.Component {
		return layouts.Auth(p, content)
	}

	return h.RenderPageTempl(ctx, p, component)
}

func (h *Auth) ResetPasswordSubmit(ctx echo.Context) error {
	var input pages.ResetPasswordForm

	err := form.Submit(ctx, &input)

	switch err.(type) {
	case nil:
	case validator.ValidationErrors:
		return h.ResetPasswordPage(ctx)
	default:
		return err
	}

	// Hash the new password
	hash, err := h.auth.HashPassword(input.Password)
	if err != nil {
		return fail(err, "unable to hash password")
	}

	// Get the requesting user
	usr := ctx.Get(context.UserKey).(*sqlc.User)

	// Update the user
	err = h.db.C.UpdateUserPassword(ctx.Request().Context(), sqlc.UpdateUserPasswordParams{
		Password: hash,
		ID:       usr.ID,
	})
	if err != nil {
		return fail(err, "unable to update password")
	}

	// Delete all password tokens for this user
	err = h.auth.DeletePasswordTokens(ctx, usr.ID)
	if err != nil {
		return fail(err, "unable to delete password tokens")
	}

	msg.Success(ctx, "Your password has been updated.")
	return redirect.New(ctx).
		Route(routeNameLogin).
		Go()
}

func (h *Auth) VerifyEmail(ctx echo.Context) error {
	token := ctx.Param("token")
	email, err := h.auth.ValidateEmailVerificationToken(token)
	if err != nil {
		msg.Warning(ctx, "The link is either invalid or has expired.")
		return redirect.New(ctx).
			Route(routeNameHome).
			Go()
	}

	err = h.db.C.UpdateUserSetVerified(ctx.Request().Context(), email)
	if err != nil {
		return fail(err, "failed to set user as verified")
	}

	msg.Success(ctx, "Your email has been successfully verified.")
	return redirect.New(ctx).
		Route(routeNameHome).
		Go()
}