/**
 * Template Library Component
 * UI for document template management
 */

import React, { useState } from 'react';
import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
import {
  Box,
  Button,
  Card,
  CardContent,
  CardHeader,
  Chip,
  Dialog,
  DialogActions,
  DialogContent,
  DialogTitle,
  TextField,
  Typography,
  Grid,
  IconButton,
  MenuItem,
  Select,
  FormControl,
  InputLabel,
} from '@mui/material';
import {
  Add as AddIcon,
  Edit as EditIcon,
  Preview as PreviewIcon,
  FileCopy as FileCopyIcon,
} from '@mui/icons-material';

interface Template {
  id: string;
  name: string;
  description?: string;
  category?: string;
  version: number;
  is_active: boolean;
}

export function TemplateLibrary() {
  const [selectedTemplate, setSelectedTemplate] = useState<Template | null>(null);
  const [createDialogOpen, setCreateDialogOpen] = useState(false);
  const [previewDialogOpen, setPreviewDialogOpen] = useState(false);
  const [categoryFilter, setCategoryFilter] = useState<string>('all');
  const queryClient = useQueryClient();

  const { data: templates, isLoading } = useQuery<Template[]>({
    queryKey: ['templates', categoryFilter],
    queryFn: async () => {
      const params = new URLSearchParams();
      if (categoryFilter !== 'all') params.append('category', categoryFilter);
      const response = await fetch(`/api/templates?${params}`);
      if (!response.ok) throw new Error('Failed to fetch templates');
      const data = await response.json();
      return data.templates || [];
    },
  });

  const createTemplate = useMutation({
    mutationFn: async (template: Partial<Template & { template_content: string }>) => {
      const response = await fetch('/api/templates', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify(template),
      });
      if (!response.ok) throw new Error('Failed to create template');
      return response.json();
    },
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ['templates'] });
      setCreateDialogOpen(false);
    },
  });

  const renderTemplate = useMutation({
    mutationFn: async ({ templateId, variables }: { templateId: string; variables: Record<string, unknown> }) => {
      const response = await fetch(`/api/templates/${templateId}/render`, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ variables }),
      });
      if (!response.ok) throw new Error('Failed to render template');
      return response.json();
    },
  });

  const handleCreateTemplate = (formData: FormData) => {
    createTemplate.mutate({
      name: formData.get('name') as string,
      description: formData.get('description') as string,
      category: formData.get('category') as string,
      template_content: formData.get('template_content') as string,
      is_active: true,
    });
  };

  const handlePreview = async (template: Template) => {
    setSelectedTemplate(template);
    // For preview, we'd typically show a form to input variables
    // For now, just open the dialog
    setPreviewDialogOpen(true);
  };

  return (
    <Box>
      <Box display="flex" justifyContent="space-between" alignItems="center" mb={3}>
        <Typography variant="h4">Template Library</Typography>
        <Box>
          <FormControl size="small" sx={{ minWidth: 120, mr: 2 }}>
            <InputLabel>Category</InputLabel>
            <Select
              value={categoryFilter}
              label="Category"
              onChange={(e) => setCategoryFilter(e.target.value)}
            >
              <MenuItem value="all">All</MenuItem>
              <MenuItem value="contract">Contract</MenuItem>
              <MenuItem value="pleading">Pleading</MenuItem>
              <MenuItem value="brief">Brief</MenuItem>
              <MenuItem value="letter">Letter</MenuItem>
            </Select>
          </FormControl>
          <Button
            variant="contained"
            startIcon={<AddIcon />}
            onClick={() => setCreateDialogOpen(true)}
          >
            New Template
          </Button>
        </Box>
      </Box>

      {isLoading ? (
        <Typography>Loading...</Typography>
      ) : (
        <Grid container spacing={3}>
          {templates?.map((template) => (
            <Grid item xs={12} sm={6} md={4} key={template.id}>
              <Card>
                <CardHeader
                  title={template.name}
                  subheader={template.category}
                  action={
                    <Box>
                      <IconButton size="small" onClick={() => handlePreview(template)}>
                        <PreviewIcon />
                      </IconButton>
                      <IconButton size="small">
                        <EditIcon />
                      </IconButton>
                    </Box>
                  }
                />
                <CardContent>
                  <Typography variant="body2" color="text.secondary" sx={{ mb: 1 }}>
                    {template.description}
                  </Typography>
                  <Box display="flex" gap={1}>
                    <Chip label={`v${template.version}`} size="small" />
                    {template.is_active && <Chip label="Active" size="small" color="success" />}
                  </Box>
                  <Button
                    fullWidth
                    variant="outlined"
                    startIcon={<FileCopyIcon />}
                    sx={{ mt: 2 }}
                    onClick={() => {
                      // Navigate to document assembly with this template
                      window.location.href = `/assembly?template=${template.id}`;
                    }}
                  >
                    Use Template
                  </Button>
                </CardContent>
              </Card>
            </Grid>
          ))}
        </Grid>
      )}

      <Dialog open={createDialogOpen} onClose={() => setCreateDialogOpen(false)} maxWidth="md" fullWidth>
        <form
          onSubmit={(e) => {
            e.preventDefault();
            handleCreateTemplate(new FormData(e.currentTarget));
          }}
        >
          <DialogTitle>Create New Template</DialogTitle>
          <DialogContent>
            <TextField
              autoFocus
              margin="dense"
              name="name"
              label="Template Name"
              fullWidth
              required
              sx={{ mb: 2 }}
            />
            <TextField
              margin="dense"
              name="description"
              label="Description"
              fullWidth
              sx={{ mb: 2 }}
            />
            <FormControl fullWidth margin="dense" sx={{ mb: 2 }}>
              <InputLabel>Category</InputLabel>
              <Select name="category" label="Category">
                <MenuItem value="contract">Contract</MenuItem>
                <MenuItem value="pleading">Pleading</MenuItem>
                <MenuItem value="brief">Brief</MenuItem>
                <MenuItem value="letter">Letter</MenuItem>
              </Select>
            </FormControl>
            <TextField
              margin="dense"
              name="template_content"
              label="Template Content"
              fullWidth
              multiline
              rows={15}
              required
              placeholder="Use {{variable}} for variables"
            />
          </DialogContent>
          <DialogActions>
            <Button onClick={() => setCreateDialogOpen(false)}>Cancel</Button>
            <Button type="submit" variant="contained">
              Create
            </Button>
          </DialogActions>
        </form>
      </Dialog>

      <Dialog open={previewDialogOpen} onClose={() => setPreviewDialogOpen(false)} maxWidth="lg" fullWidth>
        <DialogTitle>Preview: {selectedTemplate?.name}</DialogTitle>
        <DialogContent>
          <Typography>Template preview and variable input form would go here</Typography>
        </DialogContent>
        <DialogActions>
          <Button onClick={() => setPreviewDialogOpen(false)}>Close</Button>
          <Button variant="contained">Generate Document</Button>
        </DialogActions>
      </Dialog>
    </Box>
  );
}