#!/usr/bin/env bun
/**
 * `bun run stats` — the campaign dashboard, in the terminal.
 *
 * Four panes over ONE source: GET /api/stats. D1 owns SRS state, so this
 * fetches the Worker's aggregate rather than recomputing anything from work/
 * or from git — a second answer to "how far along am I" is exactly the drift
 * the campaign is built to avoid. The one local fact shown is the work/ file
 * inventory, which is inventory, not schedule. Unreachable Worker = an error,
 * never a reconstructed guess.
 *
 * The panes:
 *   Overview  campaign clock, solved counts, phase bars, recent activity
 *   Ladder    the +3/+7 rungs and the 14-day due queue
 *   Concepts  every topic by temperature — what has gone cold
 *   Activity  the campaign heatmap and the weekly gates
 *
 * Outside a TTY (a pipe, CI) it prints every pane once and exits, so the same
 * command works in a scrollback or a file.
 */
import {
  fetchStats,
  SRS_API,
  STAGES,
  TEMPERATURES,
  type Stats,
  type Temperature,
  type Topic,
} from "./api.ts";
import {
  BLUE,
  FG,
  GREEN,
  GREENS,
  LINE,
  MUTED,
  RED,
  YELLOW,
  bar,
  bold,
  cell,
  fg,
  heatCell,
  openScreen,
  padTo,
  rule,
  sparkline,
  stackedBar,
  width,
} from "./tui.ts";
import { BUCKETS, WINDOWS, solvedInBucket } from "./work.ts";

// ── shared vocabulary → colour ───────────────────────────────────

// Temperature is an action ramp, not a thermometer: green is warm enough to
// leave alone, red is the concept that wants revisiting. The band names carry
// the heat, the colours carry the urgency — and the glyphs carry both again,
// so a piped or NO_COLOR dashboard still separates the bands.
const TEMP_COLOR: Record<Temperature, string> = {
  hot: GREENS[4]!,
  fresh: GREEN,
  fading: YELLOW,
  cold: RED,
};

const TEMP_GLYPH: Record<Temperature, string> = {
  hot: "█",
  fresh: "▓",
  fading: "▒",
  cold: "░",
};

const DIFF_COLOR: Record<string, string> = { easy: GREEN, medium: YELLOW, hard: RED };

const LABEL = 15; // left-hand label column, shared by every pane

/** "2026-08-31" → "Mon 31", read as a plain calendar date, never localised. */
function dayLabel(iso: string): string {
  const [y, m, d] = iso.split("-").map(Number);
  const weekday = new Date(Date.UTC(y!, m! - 1, d!)).getUTCDay();
  return `${["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"][weekday]} ${String(d).padStart(2, "0")}`;
}

// ── overview ─────────────────────────────────────────────────────

function overview(s: Stats, cols: number): string[] {
  const bars = Math.max(10, Math.min(48, cols - LABEL - 18));
  const lines: string[] = [];

  const { day, days, week } = s.campaign;
  lines.push(rule("campaign", cols));
  lines.push(
    `${cell("Day", LABEL)}${bar(day, days, bars)}  ${fg(FG, `${day}/${days}`)}` +
      fg(MUTED, `  week ${week}`),
  );
  const streak = s.streak > 0 ? fg(GREENS[4]!, `${s.streak} day${s.streak === 1 ? "" : "s"}`) : fg(MUTED, "none");
  lines.push(`${cell("Streak", LABEL)}${streak}`);

  const total = s.difficulty.reduce((n, d) => n + d.total, 0);
  const done = s.difficulty.reduce((n, d) => n + d.done, 0);
  lines.push("");
  lines.push(rule("solved", cols));
  lines.push(
    `${cell("All", LABEL)}${bar(done, total, bars)}  ${fg(FG, `${done}/${total}`)}` +
      fg(MUTED, `  ${total > 0 ? Math.round((done / total) * 100) : 0}%`),
  );
  for (const d of s.difficulty) {
    lines.push(
      `${cell(d.difficulty, LABEL)}${bar(d.done, d.total, bars, DIFF_COLOR[d.difficulty] ?? GREEN)}` +
        `  ${fg(MUTED, `${d.done}/${d.total}`)}`,
    );
  }

  lines.push("");
  lines.push(rule("phases", cols));
  lines.push(
    `${" ".repeat(LABEL)}${fg(GREEN, "█")} ${fg(MUTED, "core")}  ${fg(BLUE, "█")} ${fg(MUTED, "optional")}  ` +
      `${fg(RED, "█")} ${fg(MUTED, "deferred")}  ${fg(LINE, "░")} ${fg(MUTED, "remaining")}`,
  );
  // Every phase bar is scaled to the LARGEST phase, not to itself: phases are
  // not the same size, and equal-length bars would hide that.
  const scale = Math.max(
    1,
    ...s.phases.map((p) => p.core_total + p.optional_total + p.deferred_total),
  );
  for (const p of s.phases) {
    const phaseDone = p.core_done + p.optional_done + p.deferred_done;
    const phaseTotal = p.core_total + p.optional_total + p.deferred_total;
    const segments = [
      { value: p.core_done, color: GREEN },
      { value: p.optional_done, color: BLUE },
      { value: p.deferred_done, color: RED },
      { value: phaseTotal - phaseDone, color: LINE, glyph: "░" },
    ];
    lines.push(
      `${cell(p.name, LABEL - 1)} ${stackedBar(segments, scale, bars)}  ${fg(MUTED, `${phaseDone}/${phaseTotal}`)}`,
    );
  }

  lines.push("");
  lines.push(rule("last 14 days", cols));
  const window = s.heat.slice(Math.max(0, day - 14), day);
  const attempts = window.reduce((n, h) => n + h.attempts, 0);
  const passes = window.reduce((n, h) => n + h.passes, 0);
  lines.push(
    `${cell("Attempts", LABEL)}${sparkline(window.map((h) => h.attempts))}  ` +
      fg(MUTED, `${attempts} attempts · ${passes} passed`),
  );

  // The one local fact on the dashboard: solutions on disk, per
  // spaced-repetition bucket. Inventory, not schedule — D1's ladder is the
  // schedule, and the Ladder pane is where it is shown. Empty scaffolds do not
  // count, the same rule close-solved.ts closes issues by.
  lines.push("");
  lines.push(rule("work/ on disk", cols));
  lines.push(
    cell("Solutions", LABEL) +
      BUCKETS.map((b) => `${fg(FG, String(solvedInBucket(b)))} ${fg(MUTED, `in work/${b}`)}`).join(
        fg(MUTED, " · "),
      ),
  );

  return lines;
}

// ── ladder ───────────────────────────────────────────────────────

function ladder(s: Stats, cols: number): string[] {
  const bars = Math.max(10, Math.min(48, cols - LABEL - 18));
  const lines: string[] = [rule("ladder", cols)];
  lines.push(fg(MUTED, `${" ".repeat(LABEL)}the review each problem owes next`));

  const rungs = STAGES.map((stage) => s.ladder[stage] ?? 0);
  const peak = Math.max(1, ...rungs);
  STAGES.forEach((stage, i) => {
    const n = rungs[i]!;
    // new is the untouched pile and retired is the finished one; only the
    // middle rungs are live work, so only they get the live colour.
    const color = stage === "new" ? LINE : stage === "retired" ? GREENS[4]! : GREEN;
    lines.push(`${cell(stage, LABEL)}${bar(n, peak, bars, color)}  ${fg(FG, String(n))}`);
  });

  lines.push("");
  lines.push(rule("due queue", cols));
  const today = s.queue[0];
  lines.push(
    fg(MUTED, `${" ".repeat(LABEL)}cumulative: everything the ladder wants by that day`) +
      (today ? fg(FG, `  ·  ${today.due} due today`) : ""),
  );
  const depth = Math.max(1, ...s.queue.map((q) => q.due));
  for (const q of s.queue) {
    const color = q.due > 3 ? RED : q.due > 0 ? GREEN : LINE;
    lines.push(
      `${cell(dayLabel(q.date), LABEL)}${bar(q.due, depth, bars, color)}  ${fg(MUTED, String(q.due))}`,
    );
  }

  return lines;
}

// ── concepts ─────────────────────────────────────────────────────

/** Coldest first, and everything the schedule has not reached yet last. */
function byUrgency(a: Topic, b: Topic): number {
  if (a.taught !== b.taught) return a.taught ? -1 : 1;
  return (
    TEMPERATURES.indexOf(b.temperature) - TEMPERATURES.indexOf(a.temperature) ||
    (b.age ?? Infinity) - (a.age ?? Infinity) ||
    a.issue - b.issue
  );
}

// Row layout: "● " + name + temp + coverage bar + done/total + last + due.
// Everything but the name is fixed, so the name absorbs the terminal width.
const TEMP_W = 7;
const COVER_W = 10;
const COUNT_W = 6;
const AGE_W = 6;
const DUE_W = 3;
const CONCEPT_FIXED = 3 + (TEMP_W + 1) + (COVER_W + 1) + (COUNT_W + 1) + (AGE_W + 1) + DUE_W + 1;

function concepts(s: Stats, cols: number): string[] {
  const lines: string[] = [rule("concepts by temperature", cols)];
  // Thresholds are the ladder's windows; print them rather than restate them.
  const bands: [Temperature, string][] = [
    ["hot", `≤${WINDOWS[0]}d`],
    ["fresh", `≤${WINDOWS[1]}d`],
    ["fading", `≤${WINDOWS[1] * 2}d`],
    ["cold", "older, or never"],
  ];
  lines.push(
    fg(MUTED, "  last exercised — ") +
      bands
        .map(([t, when]) => `${fg(TEMP_COLOR[t], `${TEMP_GLYPH[t]} ${t}`)} ${fg(MUTED, when)}`)
        .join(fg(MUTED, " · ")),
  );

  const taught = s.topics.filter((t) => t.taught);
  const counts = TEMPERATURES.map((t) => ({
    value: taught.filter((x) => x.temperature === t).length,
    color: TEMP_COLOR[t],
    glyph: TEMP_GLYPH[t],
  }));
  lines.push("");
  lines.push(`  ${stackedBar(counts, Math.max(1, taught.length), Math.max(10, Math.min(60, cols - 4)))}`);
  lines.push(
    `  ${TEMPERATURES.map((t, i) => `${fg(TEMP_COLOR[t], TEMP_GLYPH[t])} ${counts[i]!.value} ${fg(MUTED, t)}`).join("  ")}` +
      fg(MUTED, `   of ${taught.length} taught so far`),
  );

  const nameW = Math.max(12, Math.min(34, cols - CONCEPT_FIXED));
  lines.push("");
  lines.push(
    fg(
      MUTED,
      `   ${cell("concept", nameW)} ${cell("temp", TEMP_W)} ` +
        `${cell("coverage", COVER_W + 1 + COUNT_W)} ${cell("last", AGE_W)} ${cell("due", DUE_W, "right")}`,
    ),
  );

  for (const t of s.topics.slice().sort(byUrgency)) {
    // An unreached concept has no temperature to report — it shows the week
    // the schedule gets to it instead, so the list stays one list.
    const color = t.taught ? TEMP_COLOR[t.temperature] : LINE;
    const age =
      !t.taught ? "—" : t.age === null ? "never" : t.age <= 0 ? "today" : `${t.age}d`;
    lines.push(
      ` ${fg(color, t.taught ? TEMP_GLYPH[t.temperature] : "·")} ${fg(t.taught ? FG : MUTED, cell(t.name, nameW))} ` +
        `${fg(color, cell(t.taught ? t.temperature : `wk ${t.week ?? "?"}`, TEMP_W))} ` +
        `${bar(t.done, t.total, COVER_W, t.taught ? GREEN : LINE)} ` +
        `${fg(MUTED, cell(`${t.done}/${t.total}`, COUNT_W))} ${fg(MUTED, cell(age, AGE_W))} ` +
        `${t.due > 0 ? fg(GREEN, cell(String(t.due), DUE_W, "right")) : fg(LINE, cell("·", DUE_W, "right"))}`,
    );
  }

  return lines;
}

// ── activity ─────────────────────────────────────────────────────

const WEEKDAYS = ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"];

function activity(s: Stats, cols: number): string[] {
  const lines: string[] = [rule("attempts per campaign day", cols)];
  lines.push(fg(MUTED, "  the README heatmap, same ramp — Sunday is the rest day"));
  lines.push("");

  // CAMPAIGN_START is a Monday, so the grid is simply the series in weeks of
  // seven: column = week, row = weekday, exactly as the SVG lays it out.
  const weeks = Math.ceil(s.heat.length / 7);
  lines.push(
    `      ${fg(MUTED, Array.from({ length: weeks }, (_, w) => ` ${String(w + 1).padStart(2)}`).join(""))}`,
  );
  WEEKDAYS.forEach((name, row) => {
    const cells = Array.from({ length: weeks }, (_, w) => {
      const entry = s.heat[w * 7 + row];
      if (entry === undefined) return "   ";
      // The marker sits in the gutter, not inside the cell: a foreground
      // escape within a background run would end the background early.
      const marker = s.campaign.day - 1 === w * 7 + row ? fg(FG, "▸") : " ";
      return marker + heatCell(entry.attempts, "  ");
    }).join("");
    lines.push(`  ${fg(MUTED, cell(name, 4))}${cells}`);
  });
  lines.push("");
  lines.push(
    `  ${fg(MUTED, "less ")}${GREENS.map((_, level) => heatCell(level, "  ")).join("")}${fg(MUTED, " more")}` +
      fg(MUTED, "   · one cell per day, colour = attempts, ▸ marks today"),
  );

  lines.push("");
  lines.push(rule("weekly gates", cols));
  if (s.gates.length === 0) {
    lines.push(fg(MUTED, "  no gate has been scored yet"));
  }
  const gateW = Math.max(10, Math.min(24, cols - 30));
  for (const g of s.gates) {
    // Gates were stored as an integer percent before they were stored as a
    // fraction; both are in the table, so normalise on read.
    const rate = g.pass_rate === null ? null : g.pass_rate <= 1 ? g.pass_rate : g.pass_rate / 100;
    const color = rate === null ? LINE : rate >= 0.7 ? GREEN : RED;
    lines.push(
      `  ${fg(FG, cell(`Week ${g.week}`, 9))}` +
        `${bar(rate ?? 0, 1, gateW, color)}` +
        `  ${fg(color, cell(rate === null ? "open" : `${Math.round(rate * 100)}%`, 5))}` +
        `  ${fg(MUTED, g.issue === null ? "" : `#${g.issue}`)}${fg(MUTED, g.closed_on ? `  closed ${g.closed_on}` : "")}`,
    );
  }

  return lines;
}

// ── panes ────────────────────────────────────────────────────────

const PANES: { name: string; render: (s: Stats, cols: number) => string[] }[] = [
  { name: "Overview", render: overview },
  { name: "Ladder", render: ladder },
  { name: "Concepts", render: concepts },
  { name: "Activity", render: activity },
];

// ── non-interactive: every pane, once ────────────────────────────

let stats: Stats;
try {
  stats = await fetchStats();
} catch (err) {
  console.error(`stats: ${err instanceof Error ? err.message : String(err)}`);
  console.error(`stats: D1 is the only source of SRS truth — nothing to fall back to (SRS_API=${SRS_API}).`);
  process.exit(1);
}

if (!process.stdout.isTTY) {
  const cols = 80;
  for (const pane of PANES) {
    console.log(bold(pane.name.toUpperCase()));
    for (const line of pane.render(stats, cols)) console.log(line);
    console.log("");
  }
  process.exit(0);
}

// ── interactive ──────────────────────────────────────────────────

let pane = 0;
let offset = 0;
let note = "";

// Quitting resolves this; the finally below is what restores the terminal, so
// a thrown render never leaves the shell in raw mode on the alternate screen.
const { promise: quit, resolve: leave } = Promise.withResolvers<void>();
const screen = openScreen(onKey, draw);

function frame(): string[] {
  const cols = screen.columns;
  const tabs = PANES.map((p, i) =>
    i === pane ? bold(fg(FG, ` ${p.name} `)) : fg(MUTED, ` ${p.name} `),
  ).join(fg(LINE, "│"));
  const clock = fg(MUTED, `day ${stats.campaign.day}/${stats.campaign.days} · streak ${stats.streak}  `);
  const header = padTo(tabs, Math.max(0, cols - width(clock))) + clock;

  // header + rule + body + footer fills the terminal exactly.
  const body = PANES[pane]!.render(stats, cols);
  const height = Math.max(1, screen.rows - 3);
  offset = Math.max(0, Math.min(offset, Math.max(0, body.length - height)));
  const scrolled =
    body.length > height ? ` · ${offset + 1}-${Math.min(offset + height, body.length)}/${body.length}` : "";

  return [
    header,
    fg(LINE, "─".repeat(cols)),
    ...body.slice(offset, offset + height),
    fg(MUTED, `Tab/←→ pane · ↑↓ scroll · r refresh · q quit${scrolled}`) + (note ? `  ${fg(YELLOW, note)}` : ""),
  ];
}

function draw(): void {
  screen.draw(frame());
}

function onKey(chunk: string): void {
  switch (chunk) {
    // Raw mode delivers Ctrl-C as a byte, not a signal, so it is handled here.
    case "q":
    case "\x03":
    case "\x1b":
      leave();
      return;
    case "\t":
    case "\x1b[C":
    case "l":
      pane = (pane + 1) % PANES.length;
      offset = 0;
      break;
    case "\x1b[Z":
    case "\x1b[D":
    case "h":
      pane = (pane + PANES.length - 1) % PANES.length;
      offset = 0;
      break;
    case "\x1b[A":
    case "k":
      offset = Math.max(0, offset - 1);
      break;
    case "\x1b[B":
    case "j":
      offset += 1;
      break;
    case "r":
      note = "refreshing…";
      draw();
      void fetchStats()
        .then((fresh) => {
          stats = fresh;
          note = "";
        })
        .catch((err: unknown) => {
          note = `refresh failed: ${err instanceof Error ? err.message : String(err)}`;
        })
        .finally(draw);
      return;
    default:
      if (chunk >= "1" && chunk <= String(PANES.length)) {
        pane = Number(chunk) - 1;
        offset = 0;
        break;
      }
      return;
  }
  draw();
}

try {
  draw();
  await quit;
} finally {
  screen.close();
}