import { useState } from 'react';
import { Check, Loader2, PenLine, X } from 'lucide-react';
import { Button } from './ui/button';
import {
  Dialog,
  DialogContent,
  DialogDescription,
  DialogHeader,
  DialogTitle,
} from './ui/dialog';
import { Input } from './ui/input';
import { Badge } from './ui/badge';
import type { GameState } from '@shared/types';
import type { NationOp, RenameOp } from '@shared/protocol';

interface Props {
  game: GameState;
  open: boolean;
  onOpenChange: (open: boolean) => void;
  /** A confirm/reject request is in flight — disable the per-op controls. */
  opBusy: boolean;
  /** Apply a pending op; `edits.name` optionally overrides a rename's target name. */
  onConfirm: (index: number, edits?: { name?: string }) => void;
  /** Drop a pending op (reject / dismiss). */
  onReject: (index: number) => void;
}

/** A short, display-safe description of a pending nation op. */
function describeOp(op: NationOp, name: (ref: string) => string): string {
  if (op.kind === 'rename') return `Rename ${name(op.nationRef)} to “${op.to}”`;
  if (op.kind === 'split')
    return `Split ${name(op.nationRef)} into ${op.parts.length} nations (${op.parts
      .map((p) => p.name)
      .join(', ')})`;
  return `Merge ${op.nationRefs.map(name).join(' + ')} into “${op.into}”`;
}

/**
 * Reviews the nation ops the LLM has proposed (stored in `pendingNationOps`)
 * and lets the player apply ("LLM proposes, player confirms") or drop each one.
 * A rename shows the model's proposed name in an editable field (so the player
 * can tweak it before confirming); split and merge are declared but not yet
 * applied (P4b) — they can be dismissed but not confirmed.
 */
export default function NationOpDialog({
  game,
  open,
  onOpenChange,
  opBusy,
  onConfirm,
  onReject,
}: Props) {
  const ops = game.pendingNationOps;
  const name = (ref: string) => game.nations[ref]?.name ?? ref;
  // The player's edit to a rename's target name, keyed by pending-op index.
  // An unset entry means "use the model's proposed name" (`op.to`).
  const [edits, setEdits] = useState<Record<number, string>>({});

  return (
    <Dialog open={open} onOpenChange={onOpenChange}>
      <DialogContent className="max-w-lg" data-testid="nation-op-dialog">
        <DialogHeader>
          <DialogTitle>
            <span className="flex items-center gap-2">
              <PenLine className="size-4 text-primary" />
              Nation proposals
            </span>
          </DialogTitle>
          <DialogDescription>
            The model proposed changes to nations. Confirm to apply them (you can edit a
            rename) or reject to leave the world as it is.
          </DialogDescription>
        </DialogHeader>

        {ops.length === 0 ? (
          <p className="py-2 text-sm text-muted-foreground" data-testid="nation-op-empty">
            Nothing pending — the model hasn’t proposed any nation changes.
          </p>
        ) : (
          <ul className="max-h-[50vh] space-y-2.5 overflow-y-auto pr-1" data-testid="nation-op-list">
            {ops.map((op, i) => {
              const isRename = op.kind === 'rename';
              const finalName = isRename ? (edits[i] ?? (op as RenameOp).to).trim() : '';
              return (
                <li
                  key={`${i}-${op.kind}`}
                  className="rounded-lg border border-border/70 bg-card/50 p-3"
                  data-testid="nation-op-item"
                  data-kind={op.kind}
                >
                  <div className="mb-2 flex items-start gap-2">
                    <Badge variant="secondary" className="shrink-0 text-[11px] capitalize">
                      {op.kind}
                    </Badge>
                    <span className="min-w-0 flex-1 text-sm leading-snug">
                      {describeOp(op, name)}
                    </span>
                  </div>
                  {isRename ? (
                    <div className="space-y-2.5">
                      <Input
                        value={edits[i] ?? (op as RenameOp).to}
                        onChange={(e) => setEdits((p) => ({ ...p, [i]: e.target.value }))}
                        placeholder="New name…"
                        data-testid="nation-op-name-input"
                      />
                      <div className="flex justify-end gap-2">
                        <Button
                          variant="ghost"
                          size="sm"
                          onClick={() => onReject(i)}
                          disabled={opBusy}
                          className="text-muted-foreground hover:text-destructive"
                          data-testid="nation-op-reject"
                        >
                          <X className="size-3.5" />
                          Reject
                        </Button>
                        <Button
                          size="sm"
                          onClick={() => onConfirm(i, finalName ? { name: finalName } : undefined)}
                          disabled={opBusy}
                          data-testid="nation-op-confirm"
                        >
                          {opBusy ? <Loader2 className="size-3.5 animate-spin" /> : <Check className="size-3.5" />}
                          Confirm
                        </Button>
                      </div>
                    </div>
                  ) : (
                    <div className="flex items-center justify-between gap-2">
                      <span className="text-[11px] text-muted-foreground">
                        {op.kind === 'split' ? 'Split' : 'Merge'} isn’t available yet — dismiss to ignore it.
                      </span>
                      <Button
                        variant="ghost"
                        size="sm"
                        onClick={() => onReject(i)}
                        disabled={opBusy}
                        className="text-muted-foreground hover:text-destructive"
                        data-testid="nation-op-reject"
                      >
                        <X className="size-3.5" />
                        Dismiss
                      </Button>
                    </div>
                  )}
                </li>
              );
            })}
          </ul>
        )}
      </DialogContent>
    </Dialog>
  );
}