package app

import (
	"context"
	"errors"
	"fmt"
	"net/http"
	"net/url"

	"github.com/jackc/pgx/v5"
)

// --- email bodies ---------------------------------------------------------

func (a *App) tokenLink(raw string) string {
	return a.baseURL + "/set-password?token=" + url.QueryEscape(raw)
}

func mailText(intro, link string) string {
	return fmt.Sprintf("%s\n\nOpen this link to set your password:\n%s\n\nIf you weren't expecting this, you can ignore it.\n", intro, link)
}

func mailHTML(intro, cta, link string) string {
	return fmt.Sprintf(
		`<p>%s</p><p><a href="%s">%s</a></p><p style="color:#888;font-size:12px">If you weren't expecting this, you can ignore it.</p>`,
		intro, link, cta)
}

func (a *App) sendInvite(ctx context.Context, userID int64, email string) error {
	raw, err := a.issueToken(ctx, userID, "invite", inviteTTL)
	if err != nil {
		return err
	}
	link := a.tokenLink(raw)
	return a.mailer.Send([]string{email}, "You're invited to Spread",
		mailHTML("You've been invited to Spread. Set a password to get started.", "Set your password", link),
		mailText("You've been invited to Spread. Set a password to get started.", link))
}

func (a *App) sendReset(ctx context.Context, userID int64, email string) error {
	raw, err := a.issueToken(ctx, userID, "reset", resetTTL)
	if err != nil {
		return err
	}
	link := a.tokenLink(raw)
	return a.mailer.Send([]string{email}, "Reset your Spread password",
		mailHTML("Someone asked to reset your Spread password.", "Choose a new password", link),
		mailText("Someone asked to reset your Spread password.", link))
}

// --- forgot password ------------------------------------------------------

func (a *App) handleForgotForm(w http.ResponseWriter, r *http.Request) {
	a.render(w, r, http.StatusOK, "forgot", pageData{Title: "Reset password"})
}

func (a *App) handleForgot(w http.ResponseWriter, r *http.Request) {
	email := normEmail(r.PostFormValue("email"))

	var uid int64
	err := a.pool.QueryRow(r.Context(), `SELECT id FROM users WHERE email = $1`, email).Scan(&uid)
	if err == nil {
		if err := a.sendReset(r.Context(), uid, email); err != nil {
			http.Error(w, "could not send reset email", http.StatusInternalServerError)
			return
		}
	} else if !errors.Is(err, pgx.ErrNoRows) {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	// Always the same response, so we don't reveal which emails have accounts.
	a.render(w, r, http.StatusOK, "forgot", pageData{
		Title:  "Reset password",
		Notice: "If that email has an account, a reset link is on its way.",
	})
}

// --- set / reset password (shared by invites and resets) ------------------

func (a *App) handleSetPasswordForm(w http.ResponseWriter, r *http.Request) {
	raw := r.URL.Query().Get("token")
	if err := a.peekToken(r.Context(), raw); err != nil {
		a.render(w, r, http.StatusBadRequest, "tokenerror", pageData{Title: "Link expired"})
		return
	}
	a.render(w, r, http.StatusOK, "setpassword", pageData{Title: "Set your password", Token: raw})
}

func (a *App) handleSetPassword(w http.ResponseWriter, r *http.Request) {
	raw := r.PostFormValue("token")
	password := r.PostFormValue("password")
	confirm := r.PostFormValue("confirm")

	if len(password) < 8 || password != confirm {
		msg := "Password must be at least 8 characters."
		if password != confirm {
			msg = "Those passwords don't match."
		}
		a.render(w, r, http.StatusBadRequest, "setpassword", pageData{Title: "Set your password", Token: raw, Error: msg})
		return
	}

	userID, err := a.consumeToken(r.Context(), raw)
	if err != nil {
		a.render(w, r, http.StatusBadRequest, "tokenerror", pageData{Title: "Link expired"})
		return
	}
	if err := a.setPassword(r.Context(), userID, password); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	// Log them straight in.
	sessRaw, err := a.createSession(r.Context(), userID)
	if err != nil {
		http.Redirect(w, r, "/login", http.StatusSeeOther)
		return
	}
	a.setSessionCookie(w, sessRaw)

	dest := "/app"
	if sub, err := a.subscriberForUser(r.Context(), userID); err == nil && sub.IsInternal {
		dest = "/admin"
	}
	http.Redirect(w, r, dest, http.StatusSeeOther)
}