import { useState, useEffect, useRef } from 'preact/hooks';
import { useStore } from '@nanostores/preact';
import ModalShell from '../ui/ModalShell';
import { $isOffline } from '../../stores/networkStore.js';
import { uploadWorkOrderPhoto } from '../../stores/fleetDashboardStore.js';
import { showToast } from '../../stores/toastStore.js';

const MAX_FILE_SIZE_MB = 10;
const MAX_FILE_SIZE_BYTES = MAX_FILE_SIZE_MB * 1024 * 1024;
const ACCEPTED_TYPES = ['image/jpeg', 'image/png', 'image/webp', 'image/heic'];

export default function WorkOrderPhotoUpload({ open, workOrderId, onClose, onSuccess, onBack }) {
    const isOffline = useStore($isOffline);
    const [images, setImages] = useState([]);
    const [description, setDescription] = useState('');
    const [submitting, setSubmitting] = useState(false);
    const [progress, setProgress] = useState({ current: 0, total: 0 });
    const [error, setError] = useState('');
    const [isMounted, setIsMounted] = useState(false);
    const abortRef = useRef(null);

    useEffect(() => {
        setIsMounted(true);
        return () => {
            abortRef.current?.abort();
        };
    }, []);

    useEffect(() => {
        if (!open) {
            abortRef.current?.abort();
            abortRef.current = null;
            setImages([]);
            setDescription('');
            setError('');
            setSubmitting(false);
            setProgress({ current: 0, total: 0 });
        }
    }, [open]);

    if (!open || !isMounted) return null;

    const handleFileChange = (e) => {
        const files = Array.from(e.target.files ?? []);
        const oversized = files.filter((f) => f.size > MAX_FILE_SIZE_BYTES);
        const invalidType = files.filter((f) => !ACCEPTED_TYPES.includes(f.type));

        if (oversized.length > 0) {
            setError(`Sljedeće datoteke prelaze ${MAX_FILE_SIZE_MB} MB: ${oversized.map((f) => f.name).join(', ')}`);
            return;
        }
        if (invalidType.length > 0) {
            setError(`Nepodržan format: ${invalidType.map((f) => f.name).join(', ')}. Koristite JPG, PNG, WEBP ili HEIC.`);
            return;
        }
        setError('');
        setImages(files);
    };

    const handleSubmit = async (e) => {
        e.preventDefault();
        setError('');

        if (!workOrderId) {
            setError('Nije poznat putni nalog za koji se upload vrši.');
            return;
        }
        if (images.length === 0) {
            setError('Odaberite barem jednu fotografiju.');
            return;
        }
        if (isOffline) {
            showToast('Upload fotografija nije dostupan u offline modu.', 'error');
            return;
        }

        abortRef.current?.abort();
        abortRef.current = new AbortController();
        const { signal } = abortRef.current;

        setSubmitting(true);
        setProgress({ current: 0, total: images.length });

        let successCount = 0;
        try {
            for (const [index, file] of images.entries()) {
                if (signal.aborted) break;
                setProgress({ current: index + 1, total: images.length });
                await uploadWorkOrderPhoto(workOrderId, file, description, signal);
                successCount++;
            }

            if (!signal.aborted) {
                showToast(`${successCount} fotografija putnog naloga je uspješno uploadano.`, 'success');
                e.target.reset();
                setImages([]);
                setDescription('');
                onSuccess?.();
                onClose?.();
            }
        } catch (err) {
            if (err?.name === 'AbortError') {
                return;
            }
            setError(err?.message || 'Greška pri uploadu fotografija putnog naloga.');
            if (successCount > 0) {
                showToast(`${successCount} od ${images.length} fotografija uploadano.`, 'warning');
            }
        } finally {
            if (!signal?.aborted) {
                setSubmitting(false);
                setProgress({ current: 0, total: 0 });
                abortRef.current = null;
            }
        }
    };

    const handleCancel = () => {
        abortRef.current?.abort();
        abortRef.current = null;
        onClose?.();
    };

    return (
        <ModalShell
            onClose={handleCancel}
            overlayClassName="z-[60] p-4"
            contentClassName="flex items-center justify-center min-h-full"
            panelClassName={`w-full max-w-lg rounded-xl border border-border-hairline bg-canvas-elevated shadow-xl ${isOffline ? 'pointer-events-none opacity-50' : ''}`}
        >
            <div>
                <div className="flex items-center justify-between border-b border-border-hairline px-5 py-4">
                    <div className="flex items-center gap-3">
                        {onBack && (
                            <button
                                type="button"
                                onClick={onBack}
                                className="rounded-md px-2 py-1 text-sm text-text-muted hover:bg-canvas-deep"
                                aria-label="Natrag"
                            >
                                ← Natrag
                            </button>
                        )}
                        <div>
                            <h3 className="text-lg font-semibold text-text-main">Upload fotografija putnog naloga</h3>
                            <p className="text-xs text-text-muted mt-0.5">
                                Putni nalog #{workOrderId}
                            </p>
                        </div>
                    </div>
                    <button
                        type="button"
                        onClick={handleCancel}
                        className="rounded-md px-2 py-1 text-sm text-text-muted hover:bg-canvas-deep"
                        aria-label="Zatvori"
                    >
                        ✕
                    </button>
                </div>

                <form onSubmit={handleSubmit} className="space-y-4 px-5 py-4">
                    <div>
                        <label className="block mb-1.5 text-[11px] font-semibold text-text-muted uppercase tracking-wide">
                            Fotografije putnog naloga ({images.length} odabrano)
                        </label>
                        <input
                            type="file"
                            accept={ACCEPTED_TYPES.join(',')}
                            multiple
                            onChange={handleFileChange}
                            disabled={submitting}
                            className="block w-full text-xs text-text-muted file:mr-4 file:py-1.5 file:px-3 file:rounded-md file:border-0 file:text-xs file:font-mono file:bg-indigo-50 file:text-indigo-700 hover:file:bg-indigo-100 file:cursor-pointer transition-all disabled:opacity-50"
                        />
                        <p className="mt-1 text-[11px] text-text-muted">
                            JPG, PNG, WEBP, HEIC — max {MAX_FILE_SIZE_MB} MB po datoteci
                        </p>
                    </div>

                    {images.length > 0 && (
                        <div className="rounded-lg border border-border-hairline bg-canvas-deep p-2 max-h-32 overflow-y-auto space-y-1">
                            {images.map((file, i) => (
                                <p key={i} className="text-[10px] font-mono text-text-muted truncate">
                                    📎 [{i + 1}] {file.name}{' '}
                                    <span className="text-text-muted/60">
                                        ({(file.size / 1024).toFixed(1)} KB)
                                    </span>
                                </p>
                            ))}
                        </div>
                    )}

                    <label className="flex flex-col gap-1 text-sm">
                        <span className="font-medium text-text-main">Opis (primjenjuje se na sve slike)</span>
                        <input
                            type="text"
                            value={description}
                            onInput={(e) => setDescription(e.currentTarget.value)}
                            disabled={submitting}
                            placeholder="Npr. Slike stanja na lokaciji prije/poslije intervencije"
                            className="rounded-lg border border-border-hairline bg-canvas-base px-3 py-2 text-sm text-text-main placeholder-text-muted/40 focus:outline-none disabled:opacity-50"
                        />
                    </label>

                    {submitting && progress.total > 1 && (
                        <div>
                            <div className="flex justify-between text-[11px] text-text-muted mb-1">
                                <span>Uploading...</span>
                                <span>{progress.current}/{progress.total}</span>
                            </div>
                            <div className="h-1.5 w-full rounded-full bg-canvas-deep overflow-hidden">
                                <div
                                    className="h-full rounded-full bg-indigo-500 transition-all duration-300"
                                    style={{ width: `${(progress.current / progress.total) * 100}%` }}
                                />
                            </div>
                        </div>
                    )}

                    {error && (
                        <div className="rounded-lg border border-red-200 bg-red-50 px-3 py-2 text-sm text-red-700">
                            {error}
                        </div>
                    )}

                    <div className="flex justify-end gap-2 border-t border-border-hairline pt-3">
                        <button
                            type="button"
                            onClick={handleCancel}
                            className="rounded-lg border border-border-hairline px-4 py-2 text-sm font-medium text-text-main hover:bg-canvas-deep"
                        >
                            {submitting ? 'Prekini upload' : 'Odustani'}
                        </button>
                        <button
                            type="submit"
                            disabled={submitting || images.length === 0 || isOffline}
                            className="rounded-lg bg-indigo-600 px-4 py-2 text-sm font-semibold text-white hover:bg-indigo-700 disabled:opacity-60"
                        >
                            {submitting
                                ? `Uploading ${progress.current}/${progress.total}...`
                                : `Upload ${images.length > 0 ? images.length + ' slike' : 'fotografija'}`}
                        </button>
                    </div>
                </form>
            </div>
        </ModalShell>
    );
}