/**
 * @file The lane's git action row: ahead/behind against the upstream, and the
 * writes `POST /api/lanes/:id/git/:action` offers that are not per-file —
 * fetch, pull, push, switch branch, and create/delete a branch. Committing is
 * NOT here: it is the Changes panel's staged-only commit box, beside the
 * per-file stage/unstage/discard it commits — one way to commit, and it only
 * ever takes what the user staged.
 *
 * It renders at the top of the Changes panel (`LaneGitHeader`), its actions as
 * icons on the same row as the branch line, rather than in the lane card's ⋯ menu: that menu holds the rare and dangerous (`reset
 * worktree`), and these are the ordinary moves a lane needs several times an hour.
 * Nothing here decides what an action may do; the server does (pull is always
 * --ff-only, switch refuses a dirty tree), and this only reports what it said.
 * Failures print git's own text, because "! [rejected] non-fast-forward" tells
 * the user more than any sentence this file could write.
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

import { useRef, useState } from "react";
import { useTranslation } from "react-i18next";
import { ArrowDown, ArrowUp, GitBranch, Plus, RefreshCw, Trash2, Upload } from "lucide-react";
import { api } from "../../lib/api";
import type { LaneGitFacts, LaneWorktree } from "../../lib/types";

type Action = "fetch" | "pull" | "push" | "switch" | "branch-create" | "branch-delete";

function Btn({
  label,
  icon,
  busy,
  disabled,
  title,
  compact,
  onClick,
}: {
  label: string;
  icon?: React.ReactNode;
  busy?: boolean;
  disabled?: boolean;
  title?: string;
  /** Icon only; the label becomes the accessible name, the hint the tooltip. */
  compact?: boolean;
  onClick: () => void;
}) {
  return (
    <button
      type="button"
      onClick={onClick}
      disabled={disabled || busy}
      title={title}
      aria-label={compact ? label : undefined}
      className={`flex items-center gap-1 rounded text-[11px] text-fg-secondary transition-colors hover:bg-surface-3 hover:text-fg-primary disabled:cursor-not-allowed disabled:opacity-40 ${
        compact ? "h-6 w-6 justify-center" : "border border-border-light px-1.5 py-0.5"
      }`}
    >
      {icon}
      {!compact && label}
    </button>
  );
}

export function LaneGitBar({
  laneId,
  git,
  onChanged,
  onNewLane,
  lead,
}: {
  laneId: number;
  git: LaneGitFacts;
  /** Rendered at the start of the action row: the header's branch line, so
   *  the facts and the buttons that act on them read as one row. */
  lead?: React.ReactNode;
  /** Called after any action that could have moved the working copy. */
  onChanged: () => void;
  /** Open the Add-lane flow for a sibling worktree of this repo, optionally on
   *  a branch this bar just created. Omitted where no such flow is reachable. */
  onNewLane?: (branch?: string) => void;
}) {
  const { t } = useTranslation(["lanes"]);
  const [busy, setBusy] = useState<Action | null>(null);
  const [error, setError] = useState<string | null>(null);
  const [switching, setSwitching] = useState(false);
  const [branches, setBranches] = useState<string[] | null>(null);
  const [worktrees, setWorktrees] = useState<LaneWorktree[]>([]);
  const [picked, setPicked] = useState("");
  const [newBranch, setNewBranch] = useState("");
  // The Changes panel is not keyed by lane, so this bar outlives a lane switch.
  // All of the state above describes ONE lane — a branch picked for lane A,
  // applied after switching, would move B's HEAD — so it is reset during
  // render the moment the id changes, before anything can act on it.
  const [shownLane, setShownLane] = useState(laneId);
  // One action at a time, checked synchronously: `busy` is state, and a second
  // Enter can land before the render that disables anything.
  const inFlight = useRef(false);
  if (shownLane !== laneId) {
    setShownLane(laneId);
    setBusy(null);
    setError(null);
    setSwitching(false);
    setBranches(null);
    setWorktrees([]);
    setPicked("");
    setNewBranch("");
    inFlight.current = false;
  }
  const laneNow = useRef(laneId);
  laneNow.current = laneId;

  if (!git.available) return null;
  const dirty = git.dirty + git.untracked;

  const run = async (action: Action, body?: { branch?: string }) => {
    if (inFlight.current) return;
    inFlight.current = true;
    const lane = laneId;
    setBusy(action);
    setError(null);
    try {
      await api.lanes.gitAction(lane, action, body || {});
      // Landed after a lane switch: every write below belongs to the lane
      // no longer shown.
      if (laneNow.current !== lane) return;
      // The branch list this bar is showing is stale the moment a branch is
      // created, deleted or switched to, so it is re-read rather than patched.
      if (action === "switch" || action.startsWith("branch-")) {
        if (action === "switch") setSwitching(false);
        else setNewBranch("");
        setPicked("");
        setBranches(null);
        await refreshBranches();
      }
      onChanged();
    } catch (err) {
      // The server appends git's own stderr to the message, so this is the
      // rejection text verbatim — hence the <pre> below rather than a line.
      // ENOREMOTE is the one refusal with no git text to show: the server's
      // sentence is English and says less than a translated one.
      if (laneNow.current === lane)
        setError(
          (err as { code?: string })?.code === "ENOREMOTE"
            ? t("gitBar.errNoRemote")
            : err instanceof Error
              ? err.message
              : String(err)
        );
    } finally {
      if (laneNow.current === lane) {
        inFlight.current = false;
        setBusy(null);
      }
    }
  };

  const refreshBranches = async () => {
    try {
      const r = await api.lanes.gitBranches(laneId);
      if (laneNow.current !== laneId) return;
      setBranches(r.branches);
      setWorktrees(r.worktrees || []);
    } catch {
      if (laneNow.current === laneId) setBranches([]);
    }
  };

  const openSwitch = async () => {
    setSwitching((v) => !v);
    setError(null);
    if (branches) return;
    await refreshBranches();
  };

  const heldBy = new Map(
    worktrees.filter((w) => w.branch).map((w) => [w.branch as string, w.path])
  );

  return (
    <div data-testid="lane-git-bar" className="space-y-1">
      <div className="flex min-w-0 items-center gap-2">
        {lead}
        {/* Ahead/behind first: it is the fact that decides which of the
            buttons beside it the user actually wants. */}
        {/* Null counts with an upstream named means git could not compare
            the two (the upstream ref is gone): claiming "in sync" there
            would be a lie, so it reads as not pushed. */}
        {git.upstream && git.ahead != null && git.behind != null ? (
          <span
            data-testid="lane-git-tracking"
            title={git.upstream}
            className="flex shrink-0 items-center gap-1 font-mono text-[11px] text-fg-muted"
          >
            {(git.ahead ?? 0) > 0 && (
              <span className="flex items-center text-status-warning">
                <ArrowUp className="h-3 w-3" />
                {git.ahead}
              </span>
            )}
            {(git.behind ?? 0) > 0 && (
              <span className="flex items-center text-accent">
                <ArrowDown className="h-3 w-3" />
                {git.behind}
              </span>
            )}
            {!git.ahead && !git.behind && <span>{t("gitBar.inSync")}</span>}
          </span>
        ) : (
          git.hasRemote && (
            <span className="shrink-0 font-mono text-[11px] text-fg-muted">
              {t("gitBar.noUpstream")}
            </span>
          )
        )}

        <div className="ml-auto flex shrink-0 items-center">
          <Btn
            compact
            label={t("gitBar.fetch")}
            icon={<RefreshCw className="h-3.5 w-3.5" />}
            busy={busy === "fetch"}
            disabled={!git.hasRemote || !!busy}
            title={t("gitBar.fetchHint")}
            onClick={() => run("fetch")}
          />
          <Btn
            compact
            label={t("gitBar.pull")}
            icon={<ArrowDown className="h-3.5 w-3.5" />}
            busy={busy === "pull"}
            disabled={!git.hasRemote || !!busy}
            title={t("gitBar.pullHint")}
            onClick={() => run("pull")}
          />
          <Btn
            compact
            label={t("gitBar.push")}
            icon={<Upload className="h-3.5 w-3.5" />}
            busy={busy === "push"}
            disabled={!git.hasRemote || !!busy}
            title={t("gitBar.pushHint")}
            onClick={() => run("push")}
          />
          <Btn
            compact
            label={t("gitBar.switch")}
            icon={<GitBranch className="h-3.5 w-3.5" />}
            disabled={!!busy}
            // A dirty tree is refused server-side; saying so before the click
            // beats a red box after it.
            title={dirty > 0 ? t("gitBar.switchDirty") : t("gitBar.switchHint")}
            onClick={openSwitch}
          />
        </div>
      </div>

      {switching && (
        <div className="flex items-center gap-1.5">
          <select
            aria-label={t("gitBar.switchLabel")}
            value={picked}
            disabled={!!busy}
            onChange={(e) => setPicked(e.target.value)}
            className="min-w-0 flex-1 rounded border border-border-light bg-surface-0 px-2 py-0.5 font-mono text-[11px] text-fg-primary focus:border-accent focus:outline-none disabled:opacity-40"
          >
            <option value="">{t("gitBar.switchLabel")}</option>
            {(branches || []).map((b) => {
              const held = heldBy.get(b);
              return (
                <option key={b} value={b}>
                  {b}
                  {b === git.branch ? ` — ${t("gitBar.switchCurrent")}` : held ? ` — ${held}` : ""}
                </option>
              );
            })}
          </select>
          <Btn
            label={t("gitBar.switchApply")}
            busy={busy === "switch"}
            // A branch git already has checked out somewhere else cannot be
            // switched to — git allows one worktree per branch.
            disabled={!picked || picked === git.branch || !!heldBy.get(picked) || dirty > 0}
            title={dirty > 0 ? t("gitBar.switchDirty") : t("gitBar.switchHint")}
            onClick={() => void run("switch", { branch: picked })}
          />
          {onNewLane && (
            <Btn
              label={t("gitBar.newLane")}
              // A branch any worktree holds — this lane's own included — is
              // one `addWorktree` refuses with EBRANCHBUSY; say so up front.
              title={
                picked && (heldBy.has(picked) || picked === git.branch)
                  ? t("gitBar.newLaneHeld", {
                      path: heldBy.get(picked) ?? t("gitBar.switchCurrent"),
                    })
                  : t("gitBar.newLaneHint")
              }
              disabled={!picked || heldBy.has(picked) || picked === git.branch}
              // The sibling lane is created through the normal Add-lane flow,
              // prefilled — one provisioning path, not a second one here.
              onClick={() => onNewLane(picked)}
            />
          )}
          <Btn
            label={t("gitBar.branchDelete")}
            icon={<Trash2 className="h-3 w-3" />}
            busy={busy === "branch-delete"}
            disabled={!picked || picked === git.branch || !!heldBy.get(picked)}
            title={t("gitBar.branchDeleteHint")}
            onClick={() => void run("branch-delete", { branch: picked })}
          />
          {dirty > 0 && (
            <span className="text-[10px] text-status-warning">{t("gitBar.switchDirty")}</span>
          )}
        </div>
      )}

      {switching && (
        <div className="flex items-center gap-1.5">
          <input
            value={newBranch}
            onChange={(e) => setNewBranch(e.target.value)}
            onKeyDown={(e) => {
              if (e.key === "Enter" && newBranch.trim())
                void run("branch-create", { branch: newBranch.trim() });
            }}
            placeholder={t("gitBar.branchNewPlaceholder")}
            aria-label={t("gitBar.branchNewPlaceholder")}
            className="min-w-0 flex-1 rounded border border-border-light bg-surface-0 px-2 py-0.5 font-mono text-[11px] text-fg-primary placeholder:text-fg-muted focus:border-accent focus:outline-none"
          />
          <Btn
            label={t("gitBar.branchCreate")}
            icon={<Plus className="h-3 w-3" />}
            busy={busy === "branch-create"}
            disabled={!newBranch.trim()}
            // Creating does not switch: the point is usually a sibling lane,
            // and moving this pane's HEAD under a working agent is not.
            title={t("gitBar.branchCreateHint")}
            onClick={() => void run("branch-create", { branch: newBranch.trim() })}
          />
        </div>
      )}

      {error && (
        <pre
          role="alert"
          data-testid="lane-git-bar-error"
          className="max-h-24 overflow-auto whitespace-pre-wrap rounded border border-status-danger/40 bg-status-danger/10 px-2 py-1 text-[10px] text-status-danger"
        >
          {error}
        </pre>
      )}
    </div>
  );
}

export default LaneGitBar;