/**
 * Progress dashboard island — the expanded, always-current version of the
 * daily email footer. Rendered on /progress; fetches campaign state from the
 * SRS Worker at page load, entirely client-side, so `blume build` never
 * depends on the API being up. API_BASE is a placeholder stamped in after the
 * Worker deploys — do not inline it anywhere else.
 *
 * Invariants: the component never throws on malformed API data (a shape guard
 * downgrades to the error state), and the first frame is always the loading
 * state so server and client render identically.
 */
import { useEffect, useState, type CSSProperties } from "react";

export const client = "load";

const API_BASE = "https://srs-api.prdlk.workers.dev";

// ── /api/stats response shape ────────────────────────────────────

// Mirrors STAGES in apps/api/src/srs.ts — the ladder rungs, in order. The
// Worker ships every rung in `ladder`, zeros included.
const STAGES = ["new", "+3", "+7", "retired"] as const;

type Stage = (typeof STAGES)[number];

interface Stats {
  generated: string;
  campaign: { day: number; week: number; start: string; days: number };
  phases: {
    milestone: number;
    name: string;
    core_done: number;
    core_total: number;
    optional_done: number;
    optional_total: number;
    deferred_done: number;
    deferred_total: number;
  }[];
  ladder: Record<Stage, number>;
  /** week is the 1-based campaign week — the Worker converts from ISO. */
  gates: {
    week: number;
    issue: number | null;
    pass_rate: number | null;
    closed_on: string | null;
  }[];
  streak: number;
  queue: { date: string; due: number }[];
  recent: { date: string; attempts: number; passes: number }[];
}

function isStats(value: unknown): value is Stats {
  if (typeof value !== "object" || value === null) return false;
  const v = value as Record<string, unknown>;
  return (
    typeof v.campaign === "object" &&
    v.campaign !== null &&
    typeof v.ladder === "object" &&
    v.ladder !== null &&
    Array.isArray(v.phases) &&
    Array.isArray(v.gates) &&
    Array.isArray(v.queue) &&
    Array.isArray(v.recent) &&
    typeof v.streak === "number"
  );
}

// ── formatting ───────────────────────────────────────────────────

/** Legacy gates stored integer percent; the Worker may emit a 0–1 fraction. */
function percent(rate: number): string {
  return `${Math.round(rate <= 1 ? rate * 100 : rate)}%`;
}

/** "2026-08-24" → "Mon 24" without timezone drift. */
function dayLabel(iso: string): string {
  const d = new Date(`${iso}T00:00:00`);
  const weekday = d.toLocaleDateString("en-US", { weekday: "short" });
  return `${weekday} ${iso.slice(8)}`;
}

// ── shared styles ────────────────────────────────────────────────
// Theme tokens only, with two deliberate exceptions: the phase-bar sets get
// fixed hues (accent-blue core, yellow optional, red deferred — they must be
// distinguishable, not shades of one colour), and the last-7-days heatmap
// reuses the GREENS ramp from apps/api/src/charts.ts so the page matches the
// README/email heatmaps (level 0 stays a theme token so light mode works).

const card: CSSProperties = {
  border: "1px solid var(--blume-border)",
  borderRadius: "var(--blume-radius)",
  padding: "0.75rem 1rem",
  marginBottom: "1rem",
};

const muted: CSSProperties = {
  color: "var(--blume-muted-foreground)",
  fontSize: "0.85em",
};

const heading: CSSProperties = {
  fontWeight: 600,
  marginBottom: "0.5rem",
};

function Bar({ done, total }: { done: number; total: number }) {
  const ratio = total > 0 ? Math.min(done / total, 1) : 0;
  return (
    <span
      style={{
        display: "inline-block",
        width: "10rem",
        maxWidth: "40vw",
        height: "0.5rem",
        borderRadius: "var(--blume-radius)",
        background: "var(--blume-muted)",
        verticalAlign: "middle",
        overflow: "hidden",
      }}
    >
      <span
        style={{
          display: "block",
          width: `${ratio * 100}%`,
          height: "100%",
          background: "var(--blume-accent)",
        }}
      />
    </span>
  );
}

// ── sections ─────────────────────────────────────────────────────

function Header({ stats }: { stats: Stats }) {
  const { campaign, streak } = stats;
  return (
    <div style={{ ...card, display: "flex", gap: "1.5rem", flexWrap: "wrap" }}>
      <span>
        <strong>
          Day {campaign.day}/{campaign.days}
        </strong>
      </span>
      <span>Week {campaign.week}</span>
      <span>
        Streak: <strong>{streak}</strong> day{streak === 1 ? "" : "s"}
      </span>
      <span style={muted}>started {campaign.start}</span>
    </div>
  );
}

// One stacked bar per phase: solved core / optional / deferred segments over
// a muted track sized by the phase's total problem count, so both phase size
// and progress read at a glance.
const SETS = [
  ["core", "var(--blume-accent)"],
  ["optional", "#d29922"],
  ["deferred", "#e5534b"],
] as const;

function Phases({ stats }: { stats: Stats }) {
  const maxTotal = Math.max(
    1,
    ...stats.phases.map((p) => p.core_total + p.optional_total + p.deferred_total),
  );
  return (
    <div style={card}>
      <div style={heading}>Phases</div>
      <div style={{ display: "flex", gap: "1rem", flexWrap: "wrap", marginBottom: "0.6rem" }}>
        {SETS.map(([set, color]) => (
          <span key={set} style={muted}>
            <span
              style={{
                display: "inline-block",
                width: "0.65rem",
                height: "0.65rem",
                borderRadius: "2px",
                background: color,
                marginRight: "0.35rem",
              }}
            />
            {set}
          </span>
        ))}
      </div>
      {stats.phases.map((p) => {
        const total = p.core_total + p.optional_total + p.deferred_total;
        const done = p.core_done + p.optional_done + p.deferred_done;
        return (
          <div
            key={p.milestone}
            title={`core ${p.core_done}/${p.core_total} · optional ${p.optional_done}/${p.optional_total} · deferred ${p.deferred_done}/${p.deferred_total}`}
            style={{ display: "flex", alignItems: "center", gap: "0.75rem", padding: "0.25rem 0" }}
          >
            <span style={{ width: "9.5rem", flexShrink: 0 }}>{p.name}</span>
            <span style={{ flex: 1 }}>
              <span
                style={{
                  display: "flex",
                  width: `${(total / maxTotal) * 100}%`,
                  height: "0.65rem",
                  borderRadius: "var(--blume-radius)",
                  background: "var(--blume-muted)",
                  overflow: "hidden",
                }}
              >
                {SETS.map(([set, color]) => {
                  const solved = p[`${set}_done`];
                  return solved > 0 ? (
                    <span
                      key={set}
                      style={{ width: `${(solved / total) * 100}%`, background: color }}
                    />
                  ) : null;
                })}
              </span>
            </span>
            <span style={{ ...muted, width: "3.5rem", textAlign: "right", flexShrink: 0 }}>
              {done}/{total}
            </span>
          </div>
        );
      })}
    </div>
  );
}

function Ladder({ stats }: { stats: Stats }) {
  return (
    <div style={card}>
      <div style={heading}>SRS ladder</div>
      <div style={{ display: "flex", gap: "0.5rem", flexWrap: "wrap" }}>
        {STAGES.map((stage) => (
          <span
            key={stage}
            style={{
              background: "var(--blume-muted)",
              borderRadius: "var(--blume-radius)",
              padding: "0.35rem 0.75rem",
            }}
          >
            <span style={muted}>{stage}</span>{" "}
            <strong>{stats.ladder[stage] ?? 0}</strong>
          </span>
        ))}
      </div>
    </div>
  );
}

function Queue({ stats }: { stats: Stats }) {
  const max = Math.max(1, ...stats.queue.map((q) => q.due));
  return (
    <div style={card}>
      <div style={heading}>Review queue — next 14 days</div>
      <table style={{ borderCollapse: "collapse" }}>
        <tbody>
          {stats.queue.map((q) => (
            <tr key={q.date}>
              <td style={{ ...muted, padding: "0.1rem 1rem 0.1rem 0" }}>
                {dayLabel(q.date)}
              </td>
              <td style={{ padding: "0.1rem 0.75rem 0.1rem 0" }}>
                <Bar done={q.due} total={max} />
              </td>
              <td>{q.due}</td>
            </tr>
          ))}
        </tbody>
      </table>
    </div>
  );
}

function Gates({ stats }: { stats: Stats }) {
  return (
    <div style={card}>
      <div style={heading}>Gate log</div>
      {stats.gates.length === 0 ? (
        <span style={muted}>No gates yet — the first weekly review opens Saturday night.</span>
      ) : (
        stats.gates.map((g) => (
          <div
            key={g.week}
            style={{
              display: "flex",
              gap: "0.75rem",
              alignItems: "baseline",
              flexWrap: "wrap",
              padding: "0.15rem 0",
            }}
          >
            <span style={{ width: "4.5rem", flexShrink: 0 }}>Week {g.week}</span>
            {g.issue === null ? (
              <span style={muted}>no review issue</span>
            ) : (
              <a
                href={`https://github.com/prdlk/leetcode/issues/${g.issue}`}
                target="_blank"
                rel="noreferrer"
              >
                #{g.issue}
              </a>
            )}
            {g.pass_rate === null ? (
              <span style={muted}>in progress</span>
            ) : (
              <span>
                {percent(g.pass_rate)} passed
                {g.closed_on && <span style={muted}> · closed {g.closed_on}</span>}
              </span>
            )}
          </div>
        ))
      )}
      <div style={{ ...muted, marginTop: "0.4rem" }}>
        One gate per campaign week — scored when its review issue closes.
      </div>
    </div>
  );
}

// GREENS ramp from apps/api/src/charts.ts; level 0 swapped for the theme's
// muted token so an empty day looks right in both colour schemes.
const GREENS = [
  "var(--blume-muted)",
  "#0e4429",
  "#006d32",
  "#26a641",
  "#39d353",
];

function Recent({ stats }: { stats: Stats }) {
  return (
    <div style={card}>
      <div style={heading}>Last 7 days</div>
      <div style={{ display: "flex", gap: "0.4rem", flexWrap: "wrap" }}>
        {stats.recent.map((r) => (
          <span
            key={r.date}
            title={`${r.date}: ${r.passes}/${r.attempts} passed`}
            style={{ textAlign: "center" }}
          >
            <span
              style={{
                display: "block",
                width: "2.6rem",
                height: "2rem",
                borderRadius: "var(--blume-radius)",
                background: GREENS[Math.min(r.attempts, 4)],
              }}
            />
            <span style={{ ...muted, display: "block", marginTop: "0.25rem", fontSize: "0.75em" }}>
              {dayLabel(r.date)}
            </span>
          </span>
        ))}
      </div>
      <div style={{ ...muted, marginTop: "0.5rem", display: "flex", alignItems: "center", gap: "0.25rem" }}>
        <span>Less</span>
        {GREENS.map((color) => (
          <span
            key={color}
            style={{ display: "inline-block", width: "0.65rem", height: "0.65rem", borderRadius: "2px", background: color }}
          />
        ))}
        <span>More · colour = attempts, hover for passes</span>
      </div>
    </div>
  );
}

// ── dashboard ────────────────────────────────────────────────────

type Load =
  | { phase: "loading" }
  | { phase: "error" }
  | { phase: "ready"; stats: Stats };

export default function ProgressDashboard() {
  const [load, setLoad] = useState<Load>({ phase: "loading" });

  useEffect(() => {
    const controller = new AbortController();
    fetch(`${API_BASE}/api/stats`, { signal: controller.signal })
      .then((res) => {
        if (!res.ok) throw new Error(`HTTP ${res.status}`);
        return res.json();
      })
      .then((body: unknown) => {
        setLoad(isStats(body) ? { phase: "ready", stats: body } : { phase: "error" });
      })
      .catch(() => {
        if (!controller.signal.aborted) setLoad({ phase: "error" });
      });
    return () => controller.abort();
  }, []);

  if (load.phase === "loading") {
    return <p style={muted}>Loading progress…</p>;
  }
  if (load.phase === "error") {
    return (
      <p style={muted}>
        API unreachable — stats are served live from the SRS Worker and it did
        not respond.
      </p>
    );
  }

  const { stats } = load;
  return (
    <div>
      <Header stats={stats} />
      <Phases stats={stats} />
      <Ladder stats={stats} />
      <Queue stats={stats} />
      <Gates stats={stats} />
      <Recent stats={stats} />
      <p style={muted}>Generated {stats.generated}</p>
    </div>
  );
}