// frontend/src/shell/SteerInput.tsx
import { useEffect, useRef, useState } from "react";
import { CornerDownLeft } from "lucide-react";
import { useQuery, useQueryClient } from "@tanstack/react-query";
import { postSteer, createSession } from "../api/sessions";
import { getSettings, putSettings, type Settings } from "../api/settings";
import { listWorkspaces } from "../api/workspaces";
import { listModels } from "../api/models";
import { useSessionStore } from "../store/sessionStore";

const THINKING_LEVELS = ["low", "medium", "high"] as const;

interface Props {
  /** Active session, or null when no session has been started yet. */
  sessionId: string | null;
  /** Called with the new session id when the box starts a fresh session. */
  onSessionCreated?: (id: string) => void;
  /** Interrupt the running session, persisting its state. */
  onStop?: () => void;
  /** Lets the parent focus the composer (e.g. on "New session"). */
  inputRef?: React.Ref<HTMLTextAreaElement>;
}

export function SteerInput({ sessionId, onSessionCreated, onStop, inputRef }: Props) {
  const [text, setText] = useState("");
  const [busy, setBusy] = useState(false);
  const setLastUserEntry = useSessionStore((s) => s.setLastUserEntry);
  const setPhase = useSessionStore((s) => s.setPhase);
  const taRef = useRef<HTMLTextAreaElement | null>(null);

  // Merge our own ref (for autosizing) with the forwarded one (parent focus).
  function attachRef(el: HTMLTextAreaElement | null) {
    taRef.current = el;
    if (typeof inputRef === "function") inputRef(el);
    else if (inputRef) (inputRef as React.MutableRefObject<HTMLTextAreaElement | null>).current = el;
  }

  // Grow the textarea to fit its content (up to a cap, then it scrolls), and shrink
  // back when the text is cleared. Runs after every value change so height tracks text.
  useEffect(() => {
    const el = taRef.current;
    if (!el) return;
    el.style.height = "auto";
    el.style.height = `${Math.min(el.scrollHeight, 160)}px`;
  }, [text]);

  async function submit() {
    const trimmed = text.trim();
    if (!trimmed || busy) return;
    setBusy(true);
    try {
      if (sessionId) {
        await postSteer(sessionId, trimmed);
      } else {
        const { id } = await createSession({ question: trimmed });
        setPhase("F1"); // optimistic: paint F1 yellow during the cold start, before the first gate
        onSessionCreated?.(id);
      }
      setLastUserEntry({ kind: "input", text: trimmed });
      setText("");
    } finally {
      setBusy(false);
    }
  }

  function handleKeyDown(e: React.KeyboardEvent<HTMLTextAreaElement>) {
    // Enter sends; Shift+Enter inserts a newline (the textarea grows to fit it).
    if (e.key === "Enter" && !e.shiftKey) {
      e.preventDefault();
      submit();
    }
  }

  return (
    <div className="flex items-end gap-2">
      {sessionId && (
        <button
          type="button"
          onClick={onStop}
          title="Stop & save session"
          aria-label="Stop and save session"
          className="grid size-7 shrink-0 place-items-center rounded-md border border-border text-primary transition-colors hover:bg-muted"
        >
          <span className="block size-2.5 rounded-full bg-primary" />
        </button>
      )}
      <textarea
        ref={attachRef}
        rows={1}
        value={text}
        onChange={(e) => setText(e.target.value)}
        onKeyDown={handleKeyDown}
        placeholder={sessionId ? "Free steering (!)…" : "Ask a question to start a new session…"}
        aria-label={sessionId ? "Steering" : "New question"}
        className="max-h-40 flex-1 resize-none bg-transparent px-1 py-1 text-sm leading-relaxed outline-none placeholder:text-muted-foreground"
      />
      <button
        type="button"
        onClick={submit}
        disabled={!text.trim() || busy}
        aria-label="Send"
        title="Send"
        className="grid size-7 shrink-0 place-items-center rounded-md border border-border text-muted-foreground transition-colors hover:bg-muted hover:text-foreground disabled:pointer-events-none disabled:opacity-40"
      >
        <CornerDownLeft className="size-3.5" />
      </button>
    </div>
  );
}

/**
 * Status strip beneath the composer. Left: the active workspace selector.
 * Right: live model + thinking-level selectors (these replace the old Settings
 * dialog and persist through PUT /settings) plus a context-usage gauge
 * (placeholder until the backend reports token usage).
 */
export function ComposerFooter() {
  const qc = useQueryClient();
  const { data: settings } = useQuery({ queryKey: ["settings"], queryFn: getSettings });
  const { data: workspaces = [] } = useQuery({ queryKey: ["workspaces"], queryFn: listWorkspaces });
  const { data: modelsData } = useQuery({ queryKey: ["models"], queryFn: listModels });
  const models = modelsData?.models ?? [];

  const workspace = settings?.workspace ?? "";
  const model = settings?.model ?? "";
  const thinking = settings?.thinking ?? "medium";

  // PUT /settings replaces the whole object, so always send the merged settings.
  async function update(patch: Partial<Settings>) {
    await putSettings({ workspace, provider: settings?.provider, model, thinking, ...patch });
    qc.invalidateQueries({ queryKey: ["settings"] });
  }

  function onModelChange(id: string) {
    const m = models.find((x) => x.id === id);
    update({ model: id, provider: m?.provider });
  }

  const knownModel = models.some((m) => m.id === model);

  return (
    <div className="flex items-center justify-between gap-2 border-t border-border/60 px-3 py-1.5">
      <FooterSelect aria-label="Workspace" value={workspace} onChange={(v) => update({ workspace: v })}>
        {workspaces.length === 0 ? (
          <option value="">— workspace —</option>
        ) : (
          workspaces.map((w) => (
            <option key={w.name} value={w.name}>
              {w.name}
            </option>
          ))
        )}
      </FooterSelect>

      <div className="flex items-center gap-2">
        <FooterSelect aria-label="Model" value={model} onChange={onModelChange}>
          {models.length === 0 ? (
            <option value={model}>{model || "— model —"}</option>
          ) : (
            <>
              {!knownModel && <option value={model}>{model || "— model —"}</option>}
              {models.map((m) => (
                <option key={`${m.provider}/${m.id}`} value={m.id}>
                  {m.name}
                </option>
              ))}
            </>
          )}
        </FooterSelect>
        <FooterSelect aria-label="Thinking level" value={thinking} onChange={(v) => update({ thinking: v })} className="capitalize">
          {THINKING_LEVELS.map((l) => (
            <option key={l} value={l}>
              {l}
            </option>
          ))}
        </FooterSelect>
        <ContextGauge />
      </div>
    </div>
  );
}

/** Compact, theme-styled native select used in the composer footer. */
function FooterSelect({
  value,
  onChange,
  children,
  className,
  ...rest
}: {
  value: string;
  onChange: (value: string) => void;
  children: React.ReactNode;
  className?: string;
} & Pick<React.SelectHTMLAttributes<HTMLSelectElement>, "aria-label">) {
  return (
    <select
      value={value}
      onChange={(e) => onChange(e.target.value)}
      {...rest}
      className={[
        "max-w-[10rem] cursor-pointer truncate rounded-md border border-border bg-card px-1.5 py-0.5 text-[0.7rem] text-foreground/80 outline-none transition-colors hover:bg-muted focus:border-primary/40 focus:ring-2 focus:ring-ring/15",
        className,
      ].filter(Boolean).join(" ")}
    >
      {children}
    </select>
  );
}

/** Circular context-usage gauge. `pct` in [0,1]; 0 renders an empty track. */
function ContextGauge({ pct = 0 }: { pct?: number }) {
  const r = 6;
  const circ = 2 * Math.PI * r;
  return (
    <span
      title="Context usage"
      aria-label="Context usage"
      className="inline-flex items-center"
    >
      <svg width="16" height="16" viewBox="0 0 16 16" className="opacity-80">
        <circle cx="8" cy="8" r={r} fill="none" stroke="oklch(var(--border))" strokeWidth="2.25" />
        <circle
          cx="8"
          cy="8"
          r={r}
          fill="none"
          stroke="oklch(var(--primary))"
          strokeWidth="2.25"
          strokeLinecap="round"
          strokeDasharray={circ}
          strokeDashoffset={circ * (1 - Math.min(Math.max(pct, 0), 1))}
          transform="rotate(-90 8 8)"
        />
      </svg>
    </span>
  );
}