import type { Context, Hono } from "hono";
import { html } from "../pages/html.ts";
import { relativeTime } from "../pages/layout.ts";
import { SMTP_SECURITY, type SmtpSettings, saveConfig } from "../server/config.ts";
import { NOTIFICATION_KINDS, setting } from "../server/db.ts";
import { sendMail } from "../server/mail.ts";
import { type AdminContext, adminPage, formField, notice, textFields } from "./console.ts";
import { LABELS } from "./notifications.ts";
import { saveSettings } from "./store.ts";

type Queued = {
	id: number;
	subject: string;
	status: string;
	attempts: number;
	last_error: string;
	created_at: number;
};

const EMAIL = /^[^\s@<>]+@[^\s@<>]+$/;
const LISTED = 100;
const SHOWN: [key: keyof SmtpSettings, label: string][] = [
	["host", "host"],
	["port", "port"],
	["username", "username"],
	["from", "from address"],
	["to", "to address (yours)"],
];

/** The SMTP settings a form describes, a blank password keeping the stored one; or what is wrong. */
function candidate(fields: Record<string, string>, current?: SmtpSettings): SmtpSettings | string {
	const value = (key: string) => (fields[key] ?? "").trim();
	if (value("host") === "") return "The host is required.";
	if (/[\s\p{C}]/u.test(value("host")) || /[\s\p{C}]/u.test(value("username"))) {
		return "The host and username cannot contain spaces or control characters.";
	}
	const port = Number(value("port"));
	if (!Number.isInteger(port) || port < 1 || port > 65535) {
		return "The port is a number from 1 to 65535.";
	}
	const security = SMTP_SECURITY.find((known) => known === fields.security);
	if (!security) return "Pick a security setting.";
	for (const [key, label] of [
		["from", "from"],
		["to", "to"],
	] as const) {
		if (!EMAIL.test(value(key))) return `The ${label} address must be an email address.`;
	}
	// A password may have spaces at either end, so it is taken as typed.
	if (/\p{C}/u.test(fields.password ?? "")) {
		return "The password cannot contain control characters.";
	}
	// With no username there is no login, so no password either.
	const password = fields.password || current?.password || (value("username") ? undefined : "");
	if (password === undefined) return "A new SMTP server needs its password.";
	return {
		host: value("host"),
		port,
		security,
		username: value("username"),
		password,
		from: value("from"),
		to: value("to"),
	};
}

/** §24's Email section: SMTP settings, a test send, which kinds to email, and the queue. */
export function registerEmail(app: Hono, ctx: AdminContext): void {
	app.get("/admin/email", (c) => c.html(emailPage(c, ctx)));

	app.post("/admin/email", async (c) => {
		const fields = await textFields(c);
		const found = (id: string) =>
			ctx.kepr
				.query<{ id: number }, [number]>("SELECT id FROM email_queue WHERE id = ?")
				.get(Number(id));
		switch (fields.action) {
			case "test":
			case "save": {
				const next = candidate(fields, ctx.config.smtp);
				if (typeof next === "string") {
					return c.html(emailPage(c, ctx, { fields, error: next }), 400);
				}
				if (fields.action === "test") {
					try {
						await sendMail(next, "test email", "Kepr can send you email.\n");
					} catch (error) {
						const error_ = `The test email was not sent: ${error instanceof Error ? error.message : error}`;
						return c.html(emailPage(c, ctx, { fields, error: error_ }), 400);
					}
					const status = `Test email sent to ${next.to}. Nothing was saved.`;
					return c.html(emailPage(c, ctx, { fields, status }));
				}
				try {
					await saveConfig(ctx.configPath, { ...ctx.config, smtp: next });
				} catch (error) {
					const failed = `kepr.toml could not be written: ${error instanceof Error ? error.message : error}`;
					return c.html(emailPage(c, ctx, { fields, error: failed }), 500);
				}
				// In place: the delivery loop reads the same config object.
				ctx.config.smtp = next;
				break;
			}
			case "preferences": {
				const on = NOTIFICATION_KINDS.filter((kind) => fields[kind] === "1");
				if (on.length > 0 && !ctx.config.smtp) {
					const error = "Save the SMTP settings before emailing notifications.";
					return c.html(emailPage(c, ctx, { error }), 400);
				}
				saveSettings(
					ctx.kepr,
					Object.fromEntries(
						NOTIFICATION_KINDS.map((kind) => [`email_on_${kind}`, on.includes(kind) ? "1" : ""]),
					),
				);
				break;
			}
			case "retry":
				if (!found(fields.id ?? "")) return c.notFound();
				// A fresh start: every retry is available again.
				ctx.kepr
					.query(
						`UPDATE email_queue SET status = 'waiting', attempts = 0, next_at = ?
						WHERE id = ?`,
					)
					.run(Math.floor(Date.now() / 1000), Number(fields.id));
				break;
			case "discard":
				if (!found(fields.id ?? "")) return c.notFound();
				ctx.kepr.query("DELETE FROM email_queue WHERE id = ?").run(Number(fields.id));
				break;
			default:
				return c.text("Unknown action.", 400);
		}
		return c.redirect("/admin/email?saved=1", 303);
	});
}

function emailPage(
	c: Context,
	ctx: AdminContext,
	shown: { fields?: Record<string, string>; error?: string; status?: string } = {},
): string {
	const smtp = ctx.config.smtp;
	const value = (key: keyof SmtpSettings) =>
		shown.fields?.[key] ?? (smtp ? String(smtp[key]) : key === "port" ? "587" : "");
	const input = ([key, label]: (typeof SHOWN)[number]) =>
		html`<label class="issues-label" for="smtp-${key}">${label}</label>
<input class="issues-input mono" id="smtp-${key}" name="${key}" value="${value(key)}"
autocomplete="off" spellcheck="false">`;
	const security = value("security") || "starttls";
	const queue = ctx.kepr
		.query<Queued, [number]>(
			`SELECT id, subject, status, attempts, last_error, created_at FROM email_queue
			ORDER BY id DESC
			LIMIT ?`,
		)
		.all(LISTED);
	const action = (email: Queued, name: string, label: string) =>
		html`<form method="post" action="/admin/email">${formField(c)}
<input type="hidden" name="action" value="${name}">
<input type="hidden" name="id" value="${String(email.id)}">
<button class="issues-cancel mono" type="submit">${label}</button></form>`;
	const row = (email: Queued) => html`<article class="issue-post">
<p class="issue-post-head mono"><span class="issue-author">${email.status}${
		email.attempts > 0
			? ` · ${email.attempts} ${email.attempts === 1 ? "attempt" : "attempts"}`
			: ""
	}</span><span class="history-when">${relativeTime(email.created_at)}</span></p>
<div class="issue-text">${email.subject}</div>
${email.last_error && email.status !== "sent" && html`<p class="issues-error mono">${email.last_error}</p>`}
<div class="issues-actions">${email.status !== "sent" && action(email, "retry", "retry now")}
${action(email, "discard", "discard")}</div>
</article>`;
	const kind = (k: (typeof NOTIFICATION_KINDS)[number]) =>
		html`<label class="issues-label"><input type="checkbox" name="${k}" value="1"${
			setting(ctx.kepr, `email_on_${k}`) ? html` checked` : ""
		}${smtp ? "" : html` disabled`}> ${LABELS[k]}</label>`;
	const body = html`${notice(shown.error ?? "")}
${shown.status && html`<p class="admin-notice" role="status">${shown.status}</p>`}
<p class="admin-intro">Kepr can email you its notifications. The password is never shown.</p>
<form class="issues-form" method="post" action="/admin/email">
${formField(c)}
${SHOWN.slice(0, 2).map(input)}
<label class="issues-label" for="smtp-security">security</label>
<select class="issues-input" id="smtp-security" name="security">
${SMTP_SECURITY.map(
	(option) =>
		html`<option value="${option}"${option === security ? html` selected` : ""}>${option}</option>`,
)}
</select>
${SHOWN.slice(2, 3).map(input)}
<label class="issues-label" for="smtp-password">password</label>
<input class="issues-input mono" id="smtp-password" name="password" type="password"
autocomplete="new-password" placeholder="${smtp ? "unchanged" : ""}">
${SHOWN.slice(3).map(input)}
<p class="muted">Saved to kepr.toml, without its comments. "tls" is port 465, "starttls" usually
587, and "none" only for a relay on this machine.</p>
<div class="issues-actions">
<button class="issues-submit" type="submit" name="action" value="test">send test</button>
<button class="issues-submit" type="submit" name="action" value="save">save</button>
</div>
</form>
<section class="repo-section"><h2 class="section-label mono">email me when</h2>
<form class="issues-form" method="post" action="/admin/email">
${formField(c)}<input type="hidden" name="action" value="preferences">
${NOTIFICATION_KINDS.map(kind)}
${!smtp && html`<p class="muted">Save the SMTP settings first.</p>`}
<button class="issues-submit" type="submit"${smtp ? "" : html` disabled`}>save</button>
</form></section>
<section class="repo-section"><h2 class="section-label mono">delivery</h2>
${queue.length > 0 ? queue.map(row) : html`<p class="muted mono save-empty">nothing sent yet</p>`}
</section>`;
	return adminPage(c, ctx, "email", body);
}