/**
 * @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, commit (everything, or only what the Changes panel has
 * staged), switch branch, and create/delete a branch. Per-file staging and
 * discard live in the Changes panel, beside the file they act on.
 *
 * It renders beside the read-only git line in LaneCard rather than inside the
 * ⋯ menu: that menu holds the rare and dangerous (`reset worktree`), and these
 * are the opposite — 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 { useState } from "react";
import { useTranslation } from "react-i18next";
import {
  ArrowDown,
  ArrowUp,
  Check,
  GitBranch,
  Plus,
  RefreshCw,
  Trash2,
  Upload,
  X,
} from "lucide-react";
import { api } from "../../lib/api";
import type { LaneGitFacts, LaneWorktree } from "../../lib/types";

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

function Btn({
  label,
  icon,
  busy,
  disabled,
  title,
  onClick,
}: {
  label: string;
  icon?: React.ReactNode;
  busy?: boolean;
  disabled?: boolean;
  title?: string;
  onClick: () => void;
}) {
  return (
    <button
      type="button"
      onClick={onClick}
      disabled={disabled || busy}
      title={title}
      className="flex items-center gap-1 rounded border border-border-light px-1.5 py-0.5 text-[11px] text-fg-secondary transition-colors hover:bg-surface-2 hover:text-fg-primary disabled:cursor-not-allowed disabled:opacity-40"
    >
      {icon}
      {label}
    </button>
  );
}

export function LaneGitBar({
  laneId,
  git,
  onChanged,
  onNewLane,
}: {
  laneId: number;
  git: LaneGitFacts;
  /** 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 [committing, setCommitting] = useState(false);
  const [message, setMessage] = useState("");
  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("");

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

  const run = async (
    action: Action,
    body?: { message?: string; only?: "staged"; branch?: string }
  ) => {
    setBusy(action);
    setError(null);
    try {
      await api.lanes.gitAction(laneId, action, body || {});
      setCommitting(false);
      setMessage("");
      // 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") setSwitching(false);
      else if (action.startsWith("branch-")) {
        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.
      setError(err instanceof Error ? err.message : String(err));
    } finally {
      setBusy(null);
    }
  };

  const refreshBranches = async () => {
    try {
      const r = await api.lanes.gitBranches(laneId);
      setBranches(r.branches);
      setWorktrees(r.worktrees || []);
    } catch {
      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="mb-2 space-y-1">
      <div className="flex flex-wrap items-center gap-1.5">
        {/* Ahead/behind first: it is the fact that decides which of the
            buttons beside it the user actually wants. */}
        {git.upstream ? (
          <span
            data-testid="lane-git-tracking"
            title={git.upstream}
            className="flex 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="font-mono text-[11px] text-fg-muted">{t("gitBar.noUpstream")}</span>
          )
        )}

        <Btn
          label={t("gitBar.fetch")}
          icon={<RefreshCw className="h-3 w-3" />}
          busy={busy === "fetch"}
          disabled={!git.hasRemote || !!busy}
          title={t("gitBar.fetchHint")}
          onClick={() => run("fetch")}
        />
        <Btn
          label={t("gitBar.pull")}
          icon={<ArrowDown className="h-3 w-3" />}
          busy={busy === "pull"}
          disabled={!git.hasRemote || !!busy}
          title={t("gitBar.pullHint")}
          onClick={() => run("pull")}
        />
        <Btn
          label={t("gitBar.push")}
          icon={<Upload className="h-3 w-3" />}
          busy={busy === "push"}
          disabled={!git.hasRemote || !!busy}
          title={t("gitBar.pushHint")}
          onClick={() => run("push")}
        />
        <Btn
          label={t("gitBar.commit")}
          icon={<Check className="h-3 w-3" />}
          disabled={dirty === 0 || !!busy}
          title={dirty === 0 ? t("gitBar.commitNothing") : t("gitBar.commitHint")}
          onClick={() => {
            setCommitting((v) => !v);
            setError(null);
          }}
        />
        <Btn
          label={t("gitBar.switch")}
          icon={<GitBranch className="h-3 w-3" />}
          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>

      {committing && (
        <div className="flex items-center gap-1.5">
          <input
            autoFocus
            value={message}
            onChange={(e) => setMessage(e.target.value)}
            onKeyDown={(e) => {
              if (e.key === "Enter" && message.trim()) void run("commit", { message });
              if (e.key === "Escape") setCommitting(false);
            }}
            placeholder={t("gitBar.commitPlaceholder")}
            aria-label={t("gitBar.commitPlaceholder")}
            className="min-w-0 flex-1 rounded border border-border-light bg-surface-0 px-2 py-0.5 text-[11px] text-fg-primary placeholder:text-fg-muted focus:border-accent focus:outline-none"
          />
          <Btn
            label={t("gitBar.commitAll", { count: dirty })}
            busy={busy === "commit"}
            disabled={!message.trim()}
            onClick={() => void run("commit", { message })}
          />
          {/* The Changes panel's per-file staging only means something if a
              commit can take the index as it stands. The server answers
              ENOCHANGES when nothing is staged, and that text lands below. */}
          <Btn
            label={t("gitBar.commitStaged")}
            title={t("gitBar.commitStagedHint")}
            busy={busy === "commit"}
            disabled={!message.trim()}
            onClick={() => void run("commit", { message, only: "staged" })}
          />
          <button
            type="button"
            aria-label={t("gitBar.cancel")}
            onClick={() => setCommitting(false)}
            className="text-fg-muted hover:text-fg-primary"
          >
            <X className="h-3.5 w-3.5" />
          </button>
        </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")}
              title={t("gitBar.newLaneHint")}
              disabled={!picked}
              // 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;