'use client';

import { memo, useMemo, useState } from 'react';
import { DiffModeEnum, DiffView } from '@git-diff-view/react';
import { IconArrowBackUp, IconCopy, IconLayoutColumns, IconLayoutRows } from '@tabler/icons-react';
import { useTheme } from 'next-themes';
import { Badge } from '@kandev/ui/badge';
import { Button } from '@kandev/ui/button';
import { Tooltip, TooltipContent, TooltipTrigger } from '@kandev/ui/tooltip';
import { cn } from '@/lib/utils';
import { getLocalStorage, setLocalStorage } from '@/lib/local-storage';
import { useAppStore } from '@/components/state-provider';
import { useSessionGitStatus } from '@/hooks/use-session-git-status';

type TaskChangesPanelProps = {
  selectedDiffPath: string | null;
  onClearSelected: () => void;
};

const DEFAULT_DIFF_MODE: 'unified' | 'split' = 'unified';

const TaskChangesPanel = memo(function TaskChangesPanel({
  selectedDiffPath,
  onClearSelected,
}: TaskChangesPanelProps) {
  const [diffViewMode, setDiffViewMode] = useState<'unified' | 'split'>(() =>
    getLocalStorage('task-diff-view-mode', DEFAULT_DIFF_MODE)
  );
  const { resolvedTheme } = useTheme();
  const activeSessionId = useAppStore((state) => state.tasks.activeSessionId);
  const gitStatus = useSessionGitStatus(activeSessionId);

  // Convert git status files to array for display
  const changedFiles = useMemo(() => {
    if (!gitStatus?.files || Object.keys(gitStatus.files).length === 0) {
      return [];
    }
    return Object.values(gitStatus.files);
  }, [gitStatus]);
  const diffTargets = useMemo(
    () => (selectedDiffPath ? [selectedDiffPath] : changedFiles.map((file) => file.path)),
    [selectedDiffPath, changedFiles]
  );
  const diffModeEnum = diffViewMode === 'split' ? DiffModeEnum.Split : DiffModeEnum.Unified;
  const diffTheme = resolvedTheme === 'dark' ? 'dark' : 'light';
  const selectedFile = selectedDiffPath && gitStatus ? gitStatus.files[selectedDiffPath] : null;
  const selectedDiffContent = selectedFile?.diff ?? '';
  const isSingleDiffSelected = Boolean(selectedDiffPath && selectedFile);

  return (
    <div className="flex flex-col gap-2 h-full">
      <div className="flex items-center justify-between gap-3">
        <Badge variant="secondary" className="rounded-full text-xs">
          {selectedDiffPath ?? 'All files'}
        </Badge>
        <div className="flex items-center gap-1.5">
          {selectedDiffPath && (
            <Tooltip>
              <TooltipTrigger asChild>
                <Button
                  type="button"
                  variant="ghost"
                  size="sm"
                  className="h-7 px-2 text-xs cursor-pointer"
                  onClick={onClearSelected}
                >
                  All changes
                </Button>
              </TooltipTrigger>
              <TooltipContent>Show all changes</TooltipContent>
            </Tooltip>
          )}
          <Tooltip>
            <TooltipTrigger asChild>
              <span>
                <Button
                  type="button"
                  variant="ghost"
                  size="sm"
                  className="h-7 px-2 text-xs cursor-pointer"
                  disabled={!isSingleDiffSelected}
                  onClick={async () => {
                    if (!isSingleDiffSelected) return;
                    await navigator.clipboard.writeText(selectedDiffContent);
                  }}
                >
                  <IconCopy className="h-3.5 w-3.5" />
                </Button>
              </span>
            </TooltipTrigger>
            <TooltipContent>Copy file contents</TooltipContent>
          </Tooltip>
          <Tooltip>
            <TooltipTrigger asChild>
              <span>
                <Button
                  type="button"
                  variant="ghost"
                  size="sm"
                  className="h-7 px-2 text-xs cursor-pointer"
                  disabled={!isSingleDiffSelected}
                >
                  <IconArrowBackUp className="h-3.5 w-3.5" />
                </Button>
              </span>
            </TooltipTrigger>
            <TooltipContent>Discard changes</TooltipContent>
          </Tooltip>
          <div className="inline-flex rounded-md border border-border overflow-hidden">
            <Tooltip>
              <TooltipTrigger asChild>
                <span>
                  <Button
                    type="button"
                    variant="ghost"
                    size="sm"
                    className={cn(
                      'h-7 px-2 text-xs rounded-none cursor-pointer',
                      diffViewMode === 'unified' && 'bg-muted'
                    )}
                    onClick={() => {
                      setDiffViewMode('unified');
                      setLocalStorage('task-diff-view-mode', 'unified');
                    }}
                  >
                    <IconLayoutRows className="h-3.5 w-3.5" />
                  </Button>
                </span>
              </TooltipTrigger>
              <TooltipContent>Unified view</TooltipContent>
            </Tooltip>
            <Tooltip>
              <TooltipTrigger asChild>
                <span>
                  <Button
                    type="button"
                    variant="ghost"
                    size="sm"
                    className={cn(
                      'h-7 px-2 text-xs rounded-none cursor-pointer',
                      diffViewMode === 'split' && 'bg-muted'
                    )}
                    onClick={() => {
                      setDiffViewMode('split');
                      setLocalStorage('task-diff-view-mode', 'split');
                    }}
                  >
                    <IconLayoutColumns className="h-3.5 w-3.5" />
                  </Button>
                </span>
              </TooltipTrigger>
              <TooltipContent>Split view</TooltipContent>
            </Tooltip>
          </div>
        </div>
      </div>
      <div className="flex-1 min-h-0 overflow-y-auto rounded-lg bg-background p-3 h-full">
        {changedFiles.length === 0 ? (
          <div className="flex items-center justify-center h-full text-muted-foreground text-sm">
            No changes detected
          </div>
        ) : (
          <div className="space-y-4">
            {diffTargets.map((path) => {
              const file = gitStatus?.files?.[path];
              if (!file || !file.diff) {
                return null;
              }

              // Detect file language from extension
              const ext = path.split('.').pop() || '';
              const langMap: Record<string, string> = {
                ts: 'typescript',
                tsx: 'tsx',
                js: 'javascript',
                jsx: 'jsx',
                py: 'python',
                go: 'go',
                rs: 'rust',
                java: 'java',
                cpp: 'cpp',
                c: 'c',
                css: 'css',
                html: 'html',
                json: 'json',
                md: 'markdown',
                yaml: 'yaml',
                yml: 'yaml',
              };
              const fileLang = langMap[ext] || 'plaintext';

              return (
                <div key={path} className="space-y-2">
                  {!selectedDiffPath && (
                    <div className="flex items-center justify-between">
                      <Badge variant="secondary" className="rounded-full text-xs">
                        {path}
                      </Badge>
                    </div>
                  )}
                  <DiffView
                    data={{
                      hunks: [file.diff],
                      oldFile: { fileName: path, fileLang },
                      newFile: { fileName: path, fileLang },
                    }}
                    diffViewMode={diffModeEnum}
                    diffViewTheme={diffTheme}
                  />
                </div>
              );
            })}
          </div>
        )}
      </div>
    </div>
  );
});

export { TaskChangesPanel };