import { env } from "cloudflare:workers";
import { publicUrl } from "./events/emit";
import type { QueueMessage } from "./events/emit";

export type EmailQueueMessage = Extract<QueueMessage, { kind: "email.send" }>;
type EmailContent = { subject: string; text: string; html: string };

const HTML_ESCAPES: Record<string, string> = { "&": "&amp;", "<": "&lt;", ">": "&gt;", '"': "&quot;", "'": "&#39;" };

function escapeHtml(value: string): string {
  return value.replace(/[&<>"']/g, (char) => HTML_ESCAPES[char] ?? char);
}

function forgeName(): string {
  return env.FORGE_NAME || "gitfor";
}

function layout(heading: string, paragraphs: string[], action: { label: string; url: string } | null): string {
  const body = paragraphs.map((text) => `<p style="margin:0 0 12px;color:#d4d4d8">${escapeHtml(text)}</p>`).join("");
  const button = action
    ? `<p style="margin:20px 0"><a href="${escapeHtml(action.url)}" style="background:#f97316;color:#09090b;padding:10px 16px;border-radius:6px;text-decoration:none;font-weight:600">${escapeHtml(action.label)}</a></p>
       <p style="margin:0;color:#71717a;font-size:12px">${escapeHtml(action.url)}</p>`
    : "";
  return `<!doctype html><html><body style="margin:0;background:#09090b;font-family:'IBM Plex Sans',system-ui,sans-serif">
<div style="max-width:560px;margin:0 auto;padding:32px 24px">
<div style="color:#fb923c;font-size:11px;letter-spacing:.12em;text-transform:uppercase;margin-bottom:8px">${escapeHtml(forgeName())}</div>
<h1 style="color:#fafafa;font-size:20px;margin:0 0 16px">${escapeHtml(heading)}</h1>${body}${button}
</div></body></html>`;
}

function render(subject: string, paragraphs: string[], action: { label: string; url: string } | null): EmailContent {
  const text = [...paragraphs, ...(action ? [`${action.label}: ${action.url}`] : [])].join("\n\n");
  return { subject: `[${forgeName()}] ${subject}`, text, html: layout(subject, paragraphs, action) };
}

export const emailTemplates = {
  verifyEmail(name: string, url: string): EmailContent {
    return render(
      "Verify your email address",
      [`Hi ${name}, confirm this address to finish setting up your account.`, "The link expires in 24 hours."],
      { label: "Verify email", url },
    );
  },
  passwordReset(name: string, url: string): EmailContent {
    return render(
      "Reset your password",
      [
        `Hi ${name}, someone asked to reset the password for your account.`,
        "The link expires in one hour. If this wasn't you, you can ignore this email.",
      ],
      { label: "Choose a new password", url },
    );
  },
  securityNotice(name: string, event: string): EmailContent {
    return render(
      "Security alert",
      [`Hi ${name}, ${event}.`, "If this wasn't you, reset your password and review your security settings."],
      { label: "Review security settings", url: publicUrl("/settings/security") },
    );
  },
  notification(title: string, reason: string, url: string): EmailContent {
    return render(
      title,
      [
        `You are receiving this because of: ${reason.replace(/_/g, " ")}.`,
        "Manage notification settings in your account.",
      ],
      { label: "View on the forge", url: publicUrl(url) },
    );
  },
};

/** Queues an email; the Queue consumer delivers it through the Email Service binding with retries. */
export async function queueEmail(to: string, content: EmailContent): Promise<void> {
  const message: EmailQueueMessage = { kind: "email.send", to, ...content };
  await env.EVENTS.send(message);
}

/** Email Service only sends from verified domains, so an unset or localhost sender means email is disabled. */
export function emailConfigured(): boolean {
  const domain = env.EMAIL_FROM.match(/@([^>\s]+)/)?.[1] ?? "";
  return domain !== "" && domain !== "localhost" && domain.includes(".");
}

export async function deliverEmail(message: EmailQueueMessage): Promise<void> {
  if (!emailConfigured()) {
    console.warn(
      "Email disabled: set EMAIL_FROM to an address on a verified Email Service domain; dropping",
      message.subject,
    );
    return;
  }
  await env.EMAIL.send({
    to: message.to,
    from: env.EMAIL_FROM,
    subject: message.subject,
    text: message.text,
    html: message.html,
  });
}