/**
 * VDA 4905 Generator
 * Strictly follows BSH VDA 4905 Spec (Feb 2017)
 */
window.EDIBridge = window.EDIBridge || {};

class VDA4905Generator {
    static generate(parsed) {
        const segments = parsed.segments;
        const records = [];

        let count511 = 0, count512 = 0, count513 = 0, count514 = 0;

        // --- Helpers ---
        const getVal = (seg, elIdx, compIdx) => {
            if (!seg || !seg.elements) return '';
            const el = seg.elements[elIdx];
            if (!el) return '';
            if (Array.isArray(el)) return el[compIdx] || '';
            if (compIdx === 0) return el;
            // Fallback for flat elements: if asking for comp 1 of el 0, but el 0 is flat, maybe it's in el 1
            if (elIdx === 0 && compIdx === 1) return seg.elements[1] || '';
            return '';
        };

        const findSeg = (tag, qual) => segments.find(s => s.tag === tag && getVal(s, 0, 0) === qual);

        // --- 1. Header (Record 511) ---
        const nadBY = findSeg('NAD', 'BY');
        const nadSE = findSeg('NAD', 'SE');

        const custId = getVal(nadBY, 1, 0) || getVal(nadBY, 2, 0); // Try el 1 or 2
        const suppId = getVal(nadSE, 1, 0) || getVal(nadSE, 2, 0);

        const bgm = segments.find(s => s.tag === 'BGM');
        const docNum = bgm ? (getVal(bgm, 1, 0) || getVal(bgm, 0, 1)) : '';

        const dtm137 = findSeg('DTM', '137');
        const docVerify = dtm137 ? getVal(dtm137, 0, 1) : '';
        const docDateYYMMDD = docVerify.length === 8 ? docVerify.slice(2, 8) : (docVerify || '000000');

        // Old Release Number: Prioritize AIF (Previous)
        let rffOld = segments.find(s => s.tag === 'RFF' && ['AIF', 'AAN', 'AAL', 'PL'].includes(getVal(s, 0, 0)));
        let oldDocNum = rffOld ? getVal(rffOld, 0, 1) : '00000';

        // Old Release Date (DTM+192)
        const dtm192 = findSeg('DTM', '192');
        const oldDocVerify = dtm192 ? getVal(dtm192, 0, 1) : '';
        const oldDocDateYYMMDD = oldDocVerify.length === 8 ? oldDocVerify.slice(2, 8) : (oldDocVerify || '000000');

        records.push(this.build511(custId, suppId, docNum, docDateYYMMDD, oldDocNum));
        count511++;

        // --- 2. Loop through Articles (LIN) ---
        let currentLinData = null;
        for (let i = 0; i < segments.length; i++) {
            const s = segments[i];
            if (s.tag === 'LIN') {
                if (currentLinData) {
                    const added514 = this.processLin(currentLinData, records, custId, docNum, docDateYYMMDD, oldDocNum, oldDocDateYYMMDD);
                    count512++;
                    count513++;
                    count514 += added514;
                } else {
                    for (let k = i + 1; k < segments.length && segments[k].tag !== 'LIN'; k++) {
                        if (segments[k].tag === 'RFF' && getVal(segments[k], 0, 0) === 'AIF') {
                            oldDocNum = getVal(segments[k], 0, 1);
                            records[0] = this.build511(custId, suppId, docNum, docDateYYMMDD, oldDocNum);
                            break;
                        }
                    }
                }
                currentLinData = { lin: s, qtyDtms: [], rffs: [], pia: null, imd: null, locs: [], dtms: [] };
            } else if (currentLinData) {
                if (s.tag === 'QTY') {
                    let date = '';
                    let rffs = [];
                    for (let j = i + 1; j < segments.length; j++) {
                        const next = segments[j];
                        if (next.tag === 'QTY' || next.tag === 'LIN' || next.tag === 'UNS' || next.tag === 'CNT') break;
                        if (next.tag === 'DTM') {
                            const q = getVal(next, 0, 0);
                            if (['10', '2', '11', '64', '63', '69', '171', '50', '137', '131', '242'].includes(q)) {
                                date = getVal(next, 0, 1);
                            }
                        }
                        if (next.tag === 'RFF' || next.tag === 'DOC') {
                            rffs.push(next);
                        }
                    }
                    currentLinData.qtyDtms.push({ qtySeg: s, date, rffs });
                }
                else if (s.tag === 'RFF') currentLinData.rffs.push(s);
                else if (s.tag === 'PIA') currentLinData.pia = s;
                else if (s.tag === 'IMD') currentLinData.imd = s;
                else if (s.tag === 'LOC') currentLinData.locs.push(s);
                else if (s.tag === 'DTM') currentLinData.dtms.push(s);
            }
        }
        if (currentLinData) {
            const added514 = this.processLin(currentLinData, records, custId, docNum, docDateYYMMDD, oldDocNum, oldDocDateYYMMDD);
            count512++;
            count513++;
            count514 += added514;
        }

        // --- 3. Trailer (Record 519) ---
        records.push(this.build519(count511, count512, count513, count514));

        return records.map(r => r + '\r\n').join('');
    }

    static processLin(data, records, custId, docNum, docDate, headerOldDoc, headerOldDate) {
        const getVal = (seg, elIdx, compIdx) => {
            if (!seg || !seg.elements) return '';
            const el = seg.elements[elIdx];
            if (!el) return '';
            if (Array.isArray(el)) return el[compIdx] || '';
            if (compIdx === 0) return el;
            if (elIdx === 0 && compIdx === 1) return seg.elements[1] || '';
            return '';
        };

        const loc11 = data.locs.find(l => getVal(l, 0, 0) === '11');
        const plant = loc11 ? getVal(loc11, 1, 0) : '   ';

        const custMat = getVal(data.lin, 2, 0);

        const rffON = data.rffs.find(r => getVal(r, 0, 0) === 'ON');
        const orderNo = rffON ? getVal(rffON, 0, 1) : '';

        const rffAif = data.rffs.find(r => getVal(r, 0, 0) === 'AIF');
        const oldDocNum = rffAif ? getVal(rffAif, 0, 1) : headerOldDoc;

        const dtm192 = data.dtms.find(d => getVal(d, 0, 0) === '192');
        let oldDocDate = dtm192 ? getVal(dtm192, 0, 1) : headerOldDate;
        if (oldDocDate.length === 8) oldDocDate = oldDocDate.slice(2);

        const loc159 = data.locs.find(l => getVal(l, 0, 0) === '159');
        let unloading = loc159 ? getVal(loc159, 1, 0) : '';
        if (!unloading && loc11) unloading = getVal(loc11, 1, 0);

        let unit = 'ST';
        if (data.qtyDtms.length > 0) {
            const u = getVal(data.qtyDtms[0].qtySeg, 0, 2);
            if (u === 'PCE' || u === 'C62') unit = 'ST';
            else if (u === 'KGM') unit = 'KG';
            else if (u === 'MTR') unit = 'M ';
        }

        records.push(this.build512(plant, docNum, docDate, custMat, orderNo, unloading, unit, oldDocNum, oldDocDate));

        const schedules = [];
        for (const item of data.qtyDtms) {
            const qual = getVal(item.qtySeg, 0, 0);
            const qty = getVal(item.qtySeg, 0, 1);

            if (['1', '12', '11', '21', '113'].includes(qual)) {
                let d = item.date;
                if (!d) d = docDate;
                if (d.length === 8) d = d.slice(2);
                // VDA 4905: Quantities are usually whole numbers or scaled as needed. 
                // Removed implicit x1000 scaling as per user feedback (15000 should be 15000).
                const mappedQty = String(Math.round(parseFloat(qty) || 0));
                schedules.push({ date: d || '000000', qty: mappedQty, qual });
            }
        }

        schedules.sort((a, b) => {
            if (a.qual === '12' && b.qual !== '12') return -1;
            if (a.qual !== '12' && b.qual === '12') return 1;
            return 0;
        });

        const chunk513 = schedules.slice(0, 5);
        const chunkRest = schedules.slice(5);

        // EFZ (Eingangs-Fortschrittszahl) = QTY+70
        // QTY+194 sind einzelne Lieferschein-Mengen, NICHT die Fortschrittszahl!
        // VDA 4905: Quantities are usually whole numbers as per user requirements
        const qty70 = data.qtyDtms.find(q => getVal(q.qtySeg, 0, 0) === '70');
        const efzRaw = qty70 ? (parseFloat(getVal(qty70.qtySeg, 0, 1)) || 0) : 0;
        const efz = String(Math.round(efzRaw));

        // Pick latest candidate for head of 513
        // 48=Received, 194=Received (alt), 12=In-Transit
        let candidates = data.qtyDtms.filter(q => ['48', '194', '12'].includes(getVal(q.qtySeg, 0, 0)));
        if (candidates.length === 0) candidates = data.qtyDtms.filter(q => getVal(q.qtySeg, 0, 0) === '1');
        const lastRec = candidates.length > 0 ? candidates[candidates.length - 1] : null;

        let weDate = lastRec && lastRec.date ? lastRec.date : '';
        if (!weDate && data.dtms) {
            const dtmRec = data.dtms.find(d => ['131', '50', '171', '137', '11'].includes(getVal(d, 0, 0)));
            weDate = dtmRec ? getVal(dtmRec, 0, 1) : '';
        }
        if (weDate.length === 8) weDate = weDate.slice(2);

        // lastQty likewise without x1000 scaling
        const lastQtyRaw = lastRec ? (parseFloat(getVal(lastRec.qtySeg, 0, 1)) || 0) : 0;
        const lastQty = String(Math.round(lastQtyRaw));

        let lastDn = '';
        const dnQuals = ['AAU', 'AAK', 'VS', 'VN', 'IF', 'SI', 'RE'];
        if (lastRec && lastRec.rffs && lastRec.rffs.length > 0) {
            const rr = lastRec.rffs.find(seg => dnQuals.includes(getVal(seg, 0, 0)));
            if (rr) lastDn = getVal(rr, 0, 1);
        }
        if (!lastDn) {
            const rff = data.rffs.find(r => dnQuals.includes(getVal(r, 0, 0)));
            lastDn = rff ? getVal(rff, 0, 1) : '';
        }

        let lastDate = lastRec && lastRec.date ? lastRec.date : '';
        if (!lastDate && data.dtms) {
            const dtmL = data.dtms.find(d => ['11', '171', '137', '131', '50'].includes(getVal(d, 0, 0)));
            lastDate = dtmL ? getVal(dtmL, 0, 1) : '';
        }
        if (lastDate.length === 8) lastDate = lastDate.slice(2);

        // Null-Stellung: DTM+51 Datum
        let nullStellung = '';
        if (qty70) {
            // DTM+51 folgt direkt nach QTY+70 in der DELFOR
            const qty70idx = data.qtyDtms.indexOf(qty70);
            // Suche DTM+51 in den Artikel-DTMs
            const dtm51 = data.dtms ? data.dtms.find(d => getVal(d, 0, 0) === '51') : null;
            if (dtm51) {
                nullStellung = getVal(dtm51, 0, 1);
                if (nullStellung.length === 8) nullStellung = nullStellung.slice(2);
            }
        }

        records.push(this.build513(chunk513, weDate, lastDn, lastDate, lastQty, efz, nullStellung));

        let count514 = 0;
        for (let i = 0; i < chunkRest.length; i += 8) {
            const chunk = chunkRest.slice(i, i + 8);
            records.push(this.build514(chunk));
            count514++;
        }
        return count514;
    }

    // --- Format Helpers ---
    static padN(val, len) {
        let v = String(val || '').replace(/[^0-9]/g, '');
        if (v.length > len) v = v.replace(/^0+/, '');
        return v.padStart(len, '0').slice(-len);
    }
    static padA(val, len) { return String(val || '').padEnd(len, ' ').slice(0, len); }

    // --- Builders ---

    static build511(cust, supp, docNum, date, oldDocNum) {
        let r = '51101';
        r += this.padA(cust, 9);
        r += this.padA(supp, 9);
        r += this.padN(oldDocNum || '00000', 5); // Old Trans No
        r += this.padN(docNum, 5); // New Trans No
        r += this.padN(date, 6);
        r += ''.padEnd(89, ' ');
        return r;
    }

    static build512(plant, docNum, docDate, custMat, orderNo, unloading, unit, oldDocNum, oldDocDate) {
        let r = '51201';
        r += this.padA(plant, 3);
        r += this.padN(docNum, 9);
        r += this.padN(docDate, 6);
        r += this.padN(oldDocNum || '000000000', 9);
        r += this.padN(oldDocDate || '000000', 6);
        r += this.padA(custMat, 22);
        r += this.padA('', 22);
        r += this.padA(orderNo, 12);
        r += this.padA(unloading, 5);
        r += '    ';
        r += this.padA(unit, 2);
        r += 'L';
        r += '  ';
        r += 'S';
        r += 'D      ';
        r += '01     ';
        r += '     ';
        return r;
    }

    static build513(schedules5, weDate, lastDn, lastDate, lastQty, efz, nullStellung) {
        let r = '51301';
        r += this.padN(weDate || '000000', 6);
        r += this.padN(lastDn || '00000000', 8);
        r += this.padN(lastDate || '000000', 6);
        r += this.padN(lastQty || '0', 12);
        r += this.padN(efz || '0', 10);

        for (let i = 0; i < 5; i++) {
            if (i < schedules5.length) {
                const s = schedules5[i];
                r += this.padN(s.date, 6);
                r += this.padN(s.qty, 9);
            } else {
                r += '      ';
                r += '         ';
            }
        }
        // Null-Stellung (6 Zeichen JJMMTT) am Ende von 513
        r += this.padN(nullStellung || '000000', 6);
        return r;
    }

    static build514(schedules8) {
        let r = '51401';
        for (let i = 0; i < 8; i++) {
            if (i < schedules8.length) {
                const s = schedules8[i];
                r += this.padN(s.date, 6);
                r += this.padN(s.qty, 9);
            } else {
                r += '      ';
                r += '         ';
            }
        }
        r += '   ';
        return r;
    }

    static build519(c511, c512, c513, c514) {
        let r = '51901';
        r += this.padN(c511, 7);
        r += this.padN(c512, 7);
        r += this.padN(c513, 7);
        r += this.padN(c514, 7);
        r += '0000000';
        r += '0000000';
        r += '0000001';
        r += ''.padEnd(74, ' ');
        return r;
    }
}
window.EDIBridge.VDA4905Generator = VDA4905Generator;