import { useState } from 'react';
import { Play, Trash2 } from 'lucide-react';
import { Badge } from './ui/badge';
import { Button } from './ui/button';
import { Card, CardContent, CardDescription, CardHeader, CardTitle } from './ui/card';
import {
  Dialog,
  DialogContent,
  DialogDescription,
  DialogFooter,
  DialogHeader,
  DialogTitle,
} from './ui/dialog';
import type { PresetMeta } from '@shared/types';
import type { GameSummary } from '@shared/protocol';

interface Props {
  presets: PresetMeta[];
  loading?: boolean;
  onPlay: (presetId: string) => void;
  /** Recent saved games (newest-updated first) for the "Saved games" section. */
  savedGames?: GameSummary[];
  /** The id remembered as the active game (drives the "Resume last game" button). */
  activeGameId?: string | null;
  /** Resume a saved game by id (shared by the resume button and saved-games rows). */
  onResume?: (id: string) => void;
  /** Delete a saved game by id (confirmed by a dialog in this component). */
  onDelete?: (id: string) => void;
}

/**
 * Home screen: a grid of scenario cards (each with a Play button), a prominent
 * "Resume last game" affordance, and a "Saved games" section listing prior
 * games so the user can get back into one — or delete it.
 */
export default function PresetPicker({
  presets,
  loading,
  onPlay,
  savedGames = [],
  activeGameId,
  onResume,
  onDelete,
}: Props) {
  const activeGame = activeGameId ? savedGames.find((g) => g.id === activeGameId) : undefined;
  // The game awaiting a delete confirmation (null = dialog closed).
  const [confirmDeleteId, setConfirmDeleteId] = useState<string | null>(null);
  const confirmDeleteTarget = confirmDeleteId
    ? savedGames.find((g) => g.id === confirmDeleteId)
    : undefined;

  return (
    <div className="mx-auto max-w-6xl px-6 py-10">
      <header className="mb-8">
        <h1 className="text-3xl font-bold tracking-tight">History</h1>
        <p className="mt-2 max-w-2xl text-muted-foreground">
          An AI-driven alternate-history simulator. Pick a scenario and a nation, then shape the
          world turn by turn — the LLM is the world engine.
        </p>
      </header>

      {/* Resume last game — prominent, shown whenever a game is remembered. */}
      {activeGameId && onResume && (
        <div
          data-testid="resume-bar"
          className="mb-8 rounded-xl border border-primary/30 bg-primary/5 p-3"
        >
          <Button
            data-testid="resume-last"
            className="w-full justify-between"
            onClick={() => onResume(activeGameId)}
            disabled={loading}
          >
            <span className="flex items-center gap-2">
              <Play className="size-4" />
              Resume last game
            </span>
            <span className="text-sm font-normal text-muted-foreground">
              {activeGame ? `${activeGame.presetTitle} · ${activeGame.date}` : 'Pick up where you left off'}
            </span>
          </Button>
        </div>
      )}

      <div className="grid gap-5 sm:grid-cols-2 lg:grid-cols-3">
        {presets.map((p) => (
          <Card
            key={p.id}
            className="flex flex-col transition hover:ring-1 hover:ring-primary/40"
            data-testid="preset-card"
          >
            <CardHeader>
              <div className="flex items-start justify-between gap-2">
                <CardTitle className="text-lg">{p.title}</CardTitle>
                <Badge variant="secondary" className="shrink-0 text-xs">
                  {p.startDate}
                </Badge>
              </div>
              <CardDescription className="text-sm leading-relaxed">{p.summary}</CardDescription>
            </CardHeader>
            <CardContent className="mt-auto">
              <Button className="w-full" onClick={() => onPlay(p.id)} disabled={loading}>
                Play
              </Button>
            </CardContent>
          </Card>
        ))}
      </div>

      {/* Saved games: get back into any prior game (or delete it). */}
      {savedGames.length > 0 && (
        <section className="mt-12" data-testid="saved-games">
          <h2 className="mb-4 text-xl font-bold tracking-tight">Saved games</h2>
          <div className="grid gap-4 sm:grid-cols-2 lg:grid-cols-3">
            {savedGames.map((g) => (
              <Card
                key={g.id}
                className="flex flex-col"
                data-testid="saved-game"
                data-game-id={g.id}
              >
                <CardHeader>
                  <div className="flex items-start justify-between gap-2">
                    <CardTitle className="text-base">{g.presetTitle}</CardTitle>
                    <div className="flex shrink-0 items-center gap-1">
                      <Badge variant="secondary" className="text-xs">
                        {g.date}
                      </Badge>
                      <Button
                        variant="ghost"
                        size="icon-sm"
                        className="text-muted-foreground hover:text-destructive"
                        data-testid="delete-game"
                        aria-label={`Delete ${g.presetTitle}`}
                        title="Delete this game"
                        onClick={() => setConfirmDeleteId(g.id)}
                        disabled={loading}
                      >
                        <Trash2 />
                      </Button>
                    </div>
                  </div>
                  <CardDescription className="text-sm">Turn {g.turn}</CardDescription>
                </CardHeader>
                <CardContent className="mt-auto">
                  <Button
                    variant="secondary"
                    className="w-full"
                    onClick={() => onResume?.(g.id)}
                    disabled={loading}
                  >
                    Resume
                  </Button>
                </CardContent>
              </Card>
            ))}
          </div>
        </section>
      )}

      {/* Confirm before permanently deleting a saved game. */}
      <Dialog open={confirmDeleteId !== null} onOpenChange={(o) => !o && setConfirmDeleteId(null)}>
        <DialogContent className="max-w-sm" data-testid="delete-game-confirm-dialog">
          <DialogHeader>
            <DialogTitle>Delete this game?</DialogTitle>
            <DialogDescription>
              {confirmDeleteTarget
                ? `"${confirmDeleteTarget.presetTitle}" (turn ${confirmDeleteTarget.turn}, ${confirmDeleteTarget.date}) will be permanently removed. This cannot be undone.`
                : 'This game will be permanently removed.'}
            </DialogDescription>
          </DialogHeader>
          <DialogFooter>
            <Button
              variant="outline"
              data-testid="delete-game-cancel"
              onClick={() => setConfirmDeleteId(null)}
            >
              Cancel
            </Button>
            <Button
              variant="destructive"
              data-testid="delete-game-confirm"
              onClick={() => {
                const id = confirmDeleteId;
                setConfirmDeleteId(null);
                if (id) onDelete?.(id);
              }}
            >
              Delete
            </Button>
          </DialogFooter>
        </DialogContent>
      </Dialog>
    </div>
  );
}