"use client";

import { useEffect, useState } from "react";
import { useParams, useRouter } from "next/navigation";
import { useForm } from "react-hook-form";
import { zodResolver } from "@hookform/resolvers/zod";
import * as z from "zod";
import { migrationService } from "@/lib/services/migration.service";
import { MigrationReviewQueueItem } from "@/types/migration";
import { Button } from "@/components/ui/button";
import {
  Form,
  FormControl,
  FormDescription,
  FormField,
  FormItem,
  FormLabel,
  FormMessage,
} from "@/components/ui/form";
import { Input } from "@/components/ui/input";
import { Textarea } from "@/components/ui/textarea";
import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from "@/components/ui/select";
import { ArrowLeftIcon, CheckCircleIcon, XCircleIcon } from "lucide-react";
import Link from "next/link";
import { toast } from "sonner";
import { Card, CardContent } from "@/components/ui/card";

const reviewFormSchema = z.object({
  document_number: z.string().min(1, "Document number is required"),
  subject: z.string().min(1, "Subject is required"),
  category: z.string().min(1, "Category is required"),
  document_date: z.string().optional(),
  issued_date: z.string().optional(),
  received_date: z.string().optional(),
  sender_id: z.string().optional(),
  discipline_id: z.string().optional(),
});

type ReviewFormValues = z.infer<typeof reviewFormSchema>;

export default function MigrationReviewPage() {
  const params = useParams();
  const router = useRouter();
  const id = Number(params.id);

  const [item, setItem] = useState<MigrationReviewQueueItem | null>(null);
  const [loading, setLoading] = useState(true);
  const [submitting, setSubmitting] = useState(false);

  const form = useForm<ReviewFormValues>({
    resolver: zodResolver(reviewFormSchema),
    defaultValues: {
      document_number: "",
      subject: "",
      category: "",
      document_date: "",
      issued_date: "",
      received_date: "",
      sender_id: "",
      discipline_id: "",
    },
  });

  useEffect(() => {
    if (!id) return;
    fetchItem(id);
  }, [id]);

  const fetchItem = async (itemId: number) => {
    try {
      setLoading(true);
      const res = await migrationService.getQueueItem(itemId);
      setItem(res);

      if (res) {
        // Pre-fill form from database item and aiIssues payload
        const issues = res.aiIssues || {};
        form.reset({
          document_number: res.documentNumber || "",
          subject: res.title || res.originalTitle || "",
          category: res.aiSuggestedCategory || "",
          document_date: issues.document_date || "",
          issued_date: issues.issued_date || "",
          received_date: issues.received_date || "",
          sender_id: issues.sender_id ? String(issues.sender_id) : "",
          discipline_id: issues.discipline_id ? String(issues.discipline_id) : "",
        });
      }
    } catch (error) {
      toast.error("Failed to load queue item");
    } finally {
      setLoading(false);
    }
  };

  const onSubmit = async (values: ReviewFormValues) => {
    if (!item) return;

    try {
      setSubmitting(true);
      const issues = item.aiIssues || {};

      const payload = {
        document_number: values.document_number,
        subject: values.subject,
        category: values.category,
        source_file_path: issues.source_file_path || "",
        migrated_by: "SYSTEM_IMPORT",
        batch_id: "MANUAL_REVIEW_BATCH",
        project_id: 1, // Assumption or pulled from store
        document_date: values.document_date,
        issued_date: values.issued_date,
        received_date: values.received_date,
        sender_id: values.sender_id ? Number(values.sender_id) : undefined,
        discipline_id: values.discipline_id ? Number(values.discipline_id) : undefined,
        details: {
          tags: issues.tags || [],
          ai_confidence: item.aiConfidence,
        }
      };

      // Mock idempotency key based on timestamp to ensure uniqueness per approval retry
      const idempotencyKey = `review-${item.id}-${Date.now()}`;
      await migrationService.approveQueueItem(item.id, payload, idempotencyKey);

      toast.success("Document approved and imported successfully");
      router.push("/admin/migration");
    } catch (error: unknown) {
      const err = error as { response?: { data?: { message?: string } } };
      toast.error(err?.response?.data?.message || "Failed to approve and import");
    } finally {
      setSubmitting(false);
    }
  };

  const onReject = async () => {
    if (!item || !confirm("Are you sure you want to REJECT this document? It will not be imported.")) return;

    try {
      setSubmitting(true);
      await migrationService.rejectQueueItem(item.id);
      toast.success("Document rejected");
      router.push("/admin/migration");
    } catch (error: unknown) {
      toast.error("Failed to reject document");
    } finally {
      setSubmitting(false);
    }
  };

  if (loading) {
    return <div className="py-10 text-center">Loading document data...</div>;
  }

  if (!item) {
    return <div className="py-10 text-center text-red-500">Document not found</div>;
  }

  const pdfUrl = item.aiIssues?.source_file_path
    ? migrationService.getStagingFileUrl(item.aiIssues.source_file_path)
    : null;

  return (
    <div className="flex flex-col h-[calc(100vh-6rem)] space-y-4">
      <div className="flex justify-between items-center shrink-0">
        <div className="flex items-center gap-4">
          <Link href="/admin/migration">
            <Button variant="outline" size="icon">
              <ArrowLeftIcon className="h-4 w-4" />
            </Button>
          </Link>
          <div>
            <h1 className="text-2xl font-bold tracking-tight">Review Document: {item.documentNumber}</h1>
            <p className="text-sm text-muted-foreground flex items-center gap-2">
              Status: <span className="font-semibold text-primary">{item.status}</span>
              {' | '} Confidence: <span className={item.aiConfidence && item.aiConfidence < 0.8 ? "text-red-500" : "text-green-500"}>{item.aiConfidence ? (item.aiConfidence * 100).toFixed(1) + "%" : "N/A"}</span>
            </p>
          </div>
        </div>
      </div>

      <div className="flex flex-1 gap-6 overflow-hidden">
        {/* Left Side: PDF Viewer */}
        <Card className="flex-1 hidden md:flex flex-col overflow-hidden border-2 border-primary/10 shadow-md">
          <CardContent className="p-0 flex-1 relative bg-slate-100">
            {pdfUrl ? (
              <iframe
                src={`${pdfUrl}#toolbar=0&navpanes=0`}
                className="absolute inset-0 w-full h-full"
                title="Document Viewer"
              />
            ) : (
              <div className="absolute inset-0 flex items-center justify-center text-muted-foreground">
                <p>No Source File Path found for this document</p>
              </div>
            )}
          </CardContent>
        </Card>

        {/* Right Side: Form */}
        <Card className="w-full md:w-[450px] lg:w-[500px] flex-shrink-0 flex flex-col overflow-hidden border-2 border-primary/10 shadow-md">
          <div className="p-4 border-b bg-muted/30">
            <h2 className="font-semibold text-lg flex items-center gap-2">
              Extracted Information
            </h2>
            {item.reviewReason && (
              <p className="text-sm text-red-500 mt-1 font-medium bg-red-50 p-2 rounded border border-red-100">
                Reason: {item.reviewReason}
              </p>
            )}
          </div>
          <CardContent className="flex-1 overflow-y-auto p-4 custom-scrollbar">
            <Form {...form}>
              <form onSubmit={form.handleSubmit(onSubmit)} className="space-y-4">
                <FormField
                  control={form.control}
                  name="document_number"
                  render={({ field }) => (
                    <FormItem>
                      <FormLabel>Document Number</FormLabel>
                      <FormControl>
                        <Input {...field} />
                      </FormControl>
                      <FormMessage />
                    </FormItem>
                  )}
                />
                <FormField
                  control={form.control}
                  name="subject"
                  render={({ field }) => (
                    <FormItem>
                      <FormLabel>Subject</FormLabel>
                      <FormControl>
                        <Textarea {...field} rows={3} />
                      </FormControl>
                      <FormMessage />
                    </FormItem>
                  )}
                />

                <div className="grid grid-cols-2 gap-4">
                  <FormField
                    control={form.control}
                    name="category"
                    render={({ field }) => (
                      <FormItem>
                        <FormLabel>Category</FormLabel>
                        <Select onValueChange={field.onChange} defaultValue={field.value}>
                          <FormControl>
                            <SelectTrigger>
                              <SelectValue placeholder="Select type" />
                            </SelectTrigger>
                          </FormControl>
                          <SelectContent>
                            <SelectItem value="CORR">CORR</SelectItem>
                            <SelectItem value="RFA">RFA</SelectItem>
                            <SelectItem value="LETTER">LETTER</SelectItem>
                            <SelectItem value="MEMO">MEMO</SelectItem>
                          </SelectContent>
                        </Select>
                        <FormMessage />
                      </FormItem>
                    )}
                  />
                  <FormField
                    control={form.control}
                    name="discipline_id"
                    render={({ field }) => (
                      <FormItem>
                        <FormLabel>Discipline ID</FormLabel>
                        <FormControl>
                          <Input {...field} type="number" placeholder="Optional" />
                        </FormControl>
                        <FormMessage />
                      </FormItem>
                    )}
                  />
                </div>

                <div className="grid grid-cols-2 gap-4">
                  <FormField
                    control={form.control}
                    name="document_date"
                    render={({ field }) => (
                      <FormItem>
                        <FormLabel>Doc Date</FormLabel>
                        <FormControl>
                          <Input {...field} type="date" />
                        </FormControl>
                      </FormItem>
                    )}
                  />
                  <FormField
                    control={form.control}
                    name="issued_date"
                    render={({ field }) => (
                      <FormItem>
                        <FormLabel>Issued Date</FormLabel>
                        <FormControl>
                          <Input {...field} type="date" />
                        </FormControl>
                      </FormItem>
                    )}
                  />
                </div>

                <FormField
                  control={form.control}
                  name="sender_id"
                  render={({ field }) => (
                    <FormItem>
                      <FormLabel>Sender Org ID</FormLabel>
                      <FormControl>
                        <Input {...field} type="number" placeholder="Optional" />
                      </FormControl>
                      <FormMessage />
                    </FormItem>
                  )}
                />

                {item.aiIssues?.key_points && item.aiIssues.key_points.length > 0 && (
                  <div className="mt-6 border-t pt-4">
                    <h3 className="font-semibold text-sm mb-2 text-muted-foreground">AI Extracted Key Points</h3>
                    <ul className="text-sm space-y-1 list-disc pl-4 text-muted-foreground">
                      {item.aiIssues.key_points.map((point: string, i: number) => (
                        <li key={i}>{point}</li>
                      ))}
                    </ul>
                  </div>
                )}

                <div className="flex gap-4 pt-6 mt-4 border-t sticky bottom-0 bg-background/95 backdrop-blur z-10">
                  <Button
                    type="button"
                    variant="destructive"
                    className="flex-1"
                    disabled={submitting || item.status !== 'PENDING'}
                    onClick={onReject}
                  >
                    <XCircleIcon className="w-4 h-4 mr-2" />
                    Reject
                  </Button>
                  <Button
                    type="submit"
                    className="flex-1 bg-green-600 hover:bg-green-700 text-white"
                    disabled={submitting || item.status !== 'PENDING'}
                  >
                    <CheckCircleIcon className="w-4 h-4 mr-2" />
                    {submitting ? "Processing..." : "Approve & Import"}
                  </Button>
                </div>
              </form>
            </Form>
          </CardContent>
        </Card>
      </div>
    </div>
  );
}