// Live seed interview screen.
//
// Layout retained from the M1 port: emerging-seed rail (left) + Socrates
// conversation (right). The rail now reflects the live `draft` extracted
// from the conversation; the right side is a real chat with the LM Studio
// (or Anthropic) gateway via /api/seed/turn. When Socrates flags ready (or
// the user clicks "Generate") we POST /api/seed/finalize, which generates
// the SysMLModel + creates the project, then we router-push to the editor.

"use client";

import { useCallback, useEffect, useRef, useState } from "react";
import { useRouter } from "next/navigation";
import { Sigil } from "../socrates/Sigil";

interface InterviewTurn {
  role: "socrates" | "user";
  text: string;
  pending?: boolean;
}

interface SeedDraft {
  title: string;
  problem: string;
  targetUser: string;
  desiredOutcome: string;
  initialHypothesis?: string;
  constraints?: string[];
}

const EMPTY_DRAFT: SeedDraft = {
  title: "",
  problem: "",
  targetUser: "",
  desiredOutcome: "",
};

export function SeedScreen() {
  const router = useRouter();
  const [history, setHistory] = useState<InterviewTurn[]>([]);
  const [draft, setDraft] = useState<SeedDraft>(EMPTY_DRAFT);
  const [confidence, setConfidence] = useState(0);
  const [ready, setReady] = useState(false);
  const [input, setInput] = useState("");
  const [sending, setSending] = useState(false);
  const [generating, setGenerating] = useState(false);
  const [error, setError] = useState<string | null>(null);
  const [meta, setMeta] = useState<{ provider?: string; model?: string }>({});
  const threadEndRef = useRef<HTMLDivElement | null>(null);
  const openedRef = useRef(false);

  // On mount, get Socrates' opening question.
  useEffect(() => {
    if (openedRef.current) return;
    openedRef.current = true;
    void sendImpl("", true);
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, []);

  // Auto-scroll
  useEffect(() => {
    threadEndRef.current?.scrollIntoView({ behavior: "smooth", block: "end" });
  }, [history]);

  const sendImpl = useCallback(
    async (text: string, isOpening = false) => {
      setSending(true);
      setError(null);

      const historyToSend: InterviewTurn[] = [...history];

      const userTurn: InterviewTurn | null = isOpening ? null : { role: "user", text };
      const pendingTurn: InterviewTurn = {
        role: "socrates",
        text: "thinking…",
        pending: true,
      };

      setHistory(curr => [...curr, ...(userTurn ? [userTurn] : []), pendingTurn]);

      try {
        const res = await fetch("/api/seed/turn", {
          method: "POST",
          headers: { "Content-Type": "application/json" },
          body: JSON.stringify({
            history: historyToSend,
            userText: text,
            draft,
          }),
        });
        if (!res.ok) {
          const err = await res.json().catch(() => ({}));
          throw new Error(err.error ?? `${res.status}`);
        }
        const data = (await res.json()) as {
          assistant: { text: string };
          draft: SeedDraft;
          confidence: number;
          ready: boolean;
          meta?: { provider?: string; model?: string };
        };

        setHistory(curr =>
          curr.map(t =>
            t === pendingTurn ? { role: "socrates", text: data.assistant.text } : t
          )
        );
        setDraft(data.draft);
        setConfidence(data.confidence);
        setReady(data.ready);
        if (data.meta) setMeta({ provider: data.meta.provider, model: data.meta.model });
      } catch (err) {
        const msg = err instanceof Error ? err.message : String(err);
        setError(msg);
        setHistory(curr =>
          curr.map(t =>
            t === pendingTurn ? { role: "socrates", text: `⚠ ${msg}`, pending: false } : t
          )
        );
      } finally {
        setSending(false);
      }
    },
    [history, draft]
  );

  const onSubmit = useCallback(async () => {
    const text = input.trim();
    if (!text || sending) return;
    setInput("");
    await sendImpl(text);
  }, [input, sending, sendImpl]);

  const generate = useCallback(async () => {
    if (generating) return;
    setGenerating(true);
    setError(null);
    try {
      const res = await fetch("/api/seed/finalize", {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ draft }),
      });
      if (!res.ok) {
        const err = await res.json().catch(() => ({}));
        throw new Error(err.error ?? `${res.status}`);
      }
      const data = (await res.json()) as { projectId: string };
      router.push(`/editor/${data.projectId}`);
    } catch (err) {
      const msg = err instanceof Error ? err.message : String(err);
      setError(msg);
      setGenerating(false);
    }
  }, [draft, generating, router]);

  const filledFieldsCount =
    [draft.problem, draft.targetUser, draft.desiredOutcome].filter(Boolean).length +
    (draft.initialHypothesis ? 1 : 0) +
    ((draft.constraints?.length ?? 0) > 0 ? 1 : 0);
  const canGenerate = !!draft.problem && !!draft.targetUser && !!draft.desiredOutcome;
  const confidencePct = Math.round(confidence * 100);

  return (
    <div className="seed-screen">
      <header className="seed-top">
        <div className="seed-top-left">
          <Sigil size={28} />
          <span className="seed-brand">Socrata</span>
          <span className="seed-pip">·</span>
          <span className="seed-step">Seed · {ready ? "ready" : "forming"}</span>
          {meta.model && (
            <span className="seed-meta">via {meta.provider} · {meta.model.split("/").pop()}</span>
          )}
        </div>
        <div className="seed-top-right">
          <a href="/" className="seed-mode-pill" style={{ textDecoration: "none" }}>← back</a>
        </div>
      </header>

      <div className="seed-body">
        <section className="seed-left">
          <div className="seed-section-label">Emerging seed</div>
          <div className="seed-fields">
            <Field label="Title" value={draft.title} />
            <Field label="Problem" value={draft.problem} />
            <Field label="Target user" value={draft.targetUser} />
            <Field label="Desired outcome" value={draft.desiredOutcome} />
            {draft.initialHypothesis && <Field label="Initial hypothesis" value={draft.initialHypothesis} inferred />}
            {draft.constraints && draft.constraints.length > 0 && (
              <div className="seed-field seed-field-inferred">
                <div className="seed-field-label">Constraints<span className="seed-conf">{draft.constraints.length}</span></div>
                <div className="seed-field-value">
                  <ul style={{ margin: 0, paddingLeft: 14 }}>
                    {draft.constraints.map((c, i) => <li key={i}>{c}</li>)}
                  </ul>
                </div>
              </div>
            )}
          </div>

          <div className="seed-confidence">
            <div className="seed-confidence-row">
              <span>Draft confidence</span>
              <span>{confidencePct}%</span>
            </div>
            <div className="seed-confidence-bar">
              <div className="seed-confidence-fill" style={{ width: `${confidencePct}%` }} />
            </div>
            <div className="seed-confidence-hint">
              {ready
                ? "Socrates says you're ready — click Generate to create the project."
                : `${filledFieldsCount} of 5 fields filled · keep answering to firm up the draft.`}
            </div>
          </div>

          <div style={{ marginTop: 18, display: "flex", flexDirection: "column", gap: 8 }}>
            <button
              className="seed-btn seed-btn-primary"
              type="button"
              onClick={generate}
              disabled={!canGenerate || generating}
              style={{ width: "100%" }}
            >
              {generating ? "Generating model…" : ready ? "Generate model & open editor" : canGenerate ? "Generate (early)" : "Generate (need more answers)"}
            </button>
            {error && (
              <div style={{
                padding: "6px 8px",
                background: "var(--warn-soft)",
                color: "var(--warn-strong)",
                borderRadius: 4,
                fontFamily: "var(--font-mono)",
                fontSize: 11,
              }}>
                ⚠ {error}
              </div>
            )}
          </div>
        </section>

        <section className="seed-right">
          <div className="seed-thread">
            {history.map((m, i) => (
              <div key={i} className={`seed-bubble seed-bubble-${m.role}`}>
                {m.role === "socrates" && (
                  <div className="seed-bubble-avatar">
                    <Sigil size={32} />
                  </div>
                )}
                <div className="seed-bubble-body">
                  <div className="seed-bubble-who">{m.role === "socrates" ? "Socrates" : "You"}</div>
                  <div
                    className="seed-bubble-text"
                    style={m.pending ? { opacity: 0.55, fontStyle: "italic" } : undefined}
                  >
                    {m.text}
                  </div>
                </div>
              </div>
            ))}
            <div ref={threadEndRef} />
          </div>

          <form
            className="seed-input-row"
            onSubmit={e => {
              e.preventDefault();
              void onSubmit();
            }}
          >
            <div className="seed-input">
              <span className="seed-input-prompt">›</span>
              <input
                className="seed-input-field"
                value={input}
                onChange={e => setInput(e.target.value)}
                placeholder={sending ? "Socrates is thinking…" : ready ? "Want to keep refining? Ask again." : "Reply to Socrates…"}
                disabled={sending || generating}
                autoFocus
              />
            </div>
            <div className="seed-input-actions">
              <button
                type="submit"
                className="seed-btn seed-btn-primary"
                disabled={sending || generating || !input.trim()}
              >
                Send · ⌘↵
              </button>
            </div>
          </form>
        </section>
      </div>
    </div>
  );
}

function Field({ label, value, inferred }: { label: string; value: string; inferred?: boolean }) {
  if (!value) {
    return (
      <div className="seed-field" style={{ opacity: 0.45 }}>
        <div className="seed-field-label">{label}</div>
        <div className="seed-field-value" style={{ fontStyle: "italic", color: "var(--muted)" }}>—</div>
      </div>
    );
  }
  return (
    <div className={`seed-field ${inferred ? "seed-field-inferred" : ""}`}>
      <div className="seed-field-label">{label}</div>
      <div className="seed-field-value">{value}</div>
    </div>
  );
}