// The issue drafted from a debug session — pure functions, so what the composer shows and
// what it saves are one computation, testable without a browser.
//
// The composer renders the markdown HERE, in the user's language, and the server carries it as it
// was reviewed (backend app/issues/bundle.py): the server adds no sentence of its own.
import type { ServerLogRow } from "./api";
import { FRONTEND_SHA, FRONTEND_VERSION } from "./version";

/** Where a step came from: a marker the user set, a page change, or typed in the composer. */
type StepKind = "marker" | "nav" | "manual";

export interface DraftStep {
  id: string;
  kind: StepKind;
  text: string;
  /** A screenshot was taken at this step. */
  shot?: boolean;
}

/** What the composer edits and saves (`form` in the saved draft). */
export interface DraftForm {
  title: string;
  description: string;
  steps: DraftStep[];
  /** Log row ids taken out of the evidence. */
  excluded: number[];
}

/** The steps a session suggests: every marker the user set, and the page changes between them. A
 *  page change repeated back to back is one step; a screenshot belongs to the step before it. A
 *  marker set without a label is named by its time (`clock`) — the one thing that finds it in the
 *  log — rather than left empty, where the issue would drop it. */
export function draftSteps(
  rows: readonly ServerLogRow[],
  pageName: (page: string) => string,
  clock: (ts: string) => string,
) {
  const steps: DraftStep[] = [];
  for (const row of rows) {
    if (row.source !== "web") continue;
    const attrs = row.attrs ?? {};
    if (row.event === "debug.step") {
      const label = typeof attrs.label === "string" ? attrs.label.trim() : "";
      steps.push({ id: `r${row.id}`, kind: "marker", text: label || clock(row.ts) });
    } else if (row.event === "nav.view") {
      const page = typeof attrs.page === "string" ? attrs.page : String(attrs.path ?? "");
      const text = page ? pageName(page) : "";
      const last = steps[steps.length - 1];
      if (!text || (last?.kind === "nav" && last.text === text)) continue;
      steps.push({ id: `r${row.id}`, kind: "nav", text });
    } else if (row.event === "debug.screenshot") {
      const last = steps[steps.length - 1];
      if (last) last.shot = true;
    }
  }
  return steps;
}

/** The operating system a user agent names. Checked most specific first: Android's agent also says
 *  "Linux" — and says it first — and an iPad's also says "Mac OS X". */
export function osName(ua: string): string {
  const tests: [RegExp, (m: RegExpExecArray) => string][] = [
    [/Android [\d.]+/, (m) => m[0]],
    [/(iPhone|iPad)[^)]*? OS ([\d_]+)/, (m) => `${m[1]} ${m[2]!.replace(/_/g, ".")}`],
    [/Windows NT [\d.]+/, (m) => m[0]],
    [/Mac OS X ([\d_]+)/, (m) => `macOS ${m[1]!.replace(/_/g, ".")}`],
    [/CrOS|Linux/, (m) => m[0]],
  ];
  for (const [re, name] of tests) {
    const m = re.exec(ua);
    if (m) return name(m);
  }
  return "?";
}

/** The environment table: what a developer asks first. Read from this browser at composing time —
 *  the same browser the session recorded in, or the report says which one it came from. */
export function environment(language: string): [key: string, value: string][] {
  const ua = navigator.userAgent;
  const browser =
    /Edg\/([\d.]+)/.exec(ua)?.[0] ??
    /Firefox\/([\d.]+)/.exec(ua)?.[0] ??
    /Chrome\/([\d.]+)/.exec(ua)?.[0] ??
    /Version\/([\d.]+).*Safari/.exec(ua)?.[0] ??
    ua;
  const rootPx = parseFloat(getComputedStyle(document.documentElement).fontSize) || 16;
  return [
    ["version", `${FRONTEND_VERSION} (${FRONTEND_SHA})`],
    ["browser", browser.replace("/", " ")],
    ["os", osName(ua)],
    [
      "window",
      `${window.innerWidth} × ${window.innerHeight} · ${window.devicePixelRatio}x · ${Math.round((rootPx / 16) * 100)}%`,
    ],
    ["language", language],
  ];
}

/** A table cell: a pipe or a line break would break the markdown table. */
const cell = (value: string) => value.replace(/\|/g, "\\|").replace(/\r?\n/g, " ");

export interface IssueText {
  steps: string;
  environment: string;
  envKeys: Record<string, string>;
  screenshot: string;
  attachments: string;
  clientLog: (n: number) => string;
  serverLog: (n: number) => string;
  screenshots: (n: number) => string;
  /** Shown when the evidence was cut at the server's cap. */
  truncated?: string;
}

/** The issue body as markdown: the description, the steps, the environment, the attachments. */
export function renderIssue(
  form: DraftForm,
  env: readonly [string, string][],
  counts: { client: number; server: number; screenshots: number },
  text: IssueText,
): string {
  const parts: string[] = [];
  const description = form.description.trim();
  if (description) parts.push(description);
  const steps = form.steps.filter((s) => s.text.trim());
  if (steps.length)
    parts.push(
      `### ${text.steps}\n\n` +
        steps
          .map((s, i) => `${i + 1}. ${s.text.trim()}${s.shot ? ` _(${text.screenshot})_` : ""}`)
          .join("\n"),
    );
  parts.push(
    `### ${text.environment}\n\n| | |\n|---|---|\n` +
      env.map(([k, v]) => `| ${cell(text.envKeys[k] ?? k)} | ${cell(v)} |`).join("\n"),
  );
  const attachments = [
    counts.client ? `- \`client.log\` — ${text.clientLog(counts.client)}` : "",
    counts.server ? `- \`server.log\` — ${text.serverLog(counts.server)}` : "",
    counts.screenshots ? `- ${text.screenshots(counts.screenshots)}` : "",
  ].filter(Boolean);
  if (attachments.length) {
    const cut = text.truncated ? `\n\n_${text.truncated}_` : "";
    parts.push(`### ${text.attachments}\n\n${attachments.join("\n")}${cut}`);
  }
  return parts.join("\n\n");
}