export interface PensionParsedEntry {
  fund: string;
  period_start: string; // YYYY-MM-DD
  period_end: string;
  saldo_anterior: number;
  aportes: number;
  rendimientos: number;
  retiros: number;
  traslados: number;
  comision: number;
  correccion: number;
  bonificacion: number;
  saldo_final: number;
}

function parseAmount(raw: string): number {
  const cleaned = raw.replace(/[¢\s]/g, '').replace(/,/g, '');
  const num = parseFloat(cleaned);
  return isNaN(num) ? 0 : num;
}

function parseDateDMY(raw: string): string {
  const m = raw.match(/(\d{2})\/(\d{2})\/(\d{4})/);
  if (!m) return '';
  return `${m[3]}-${m[2]}-${m[1]}`;
}

function extractAmounts(line: string): number[] {
  const matches = line.match(/¢\s*-?[\d,.]+/g);
  if (!matches) return [];
  return matches.map(parseAmount);
}

// Field labels in the order they appear in the bank statement
const FIELD_LABELS: [RegExp, string][] = [
  [/saldo\s*anterior/i, 'saldo_anterior'],
  [/aportes/i, 'aportes'],
  [/rendimientos/i, 'rendimientos'],
  [/retiros/i, 'retiros'],
  [/traslados/i, 'traslados'],
  [/comisi[oó]n/i, 'comision'],
  [/bonificaci[oó]n/i, 'bonificacion'],
];

interface BlockResult {
  funds: string[];
  fields: Record<string, number[]>;
  period_start: string;
  period_end: string;
}

function parseBlock(lines: string[]): BlockResult | null {
  const result: BlockResult = {
    funds: [],
    fields: {},
    period_start: '',
    period_end: '',
  };

  // Detect fund columns from header
  const headerLine = lines.find((l) => /resumen del per[ií]odo/i.test(l));
  if (!headerLine) return null;

  if (/\bROP\b/i.test(headerLine) && /\bFCL\b/i.test(headerLine)) {
    result.funds = ['ROP', 'FCL'];
  } else if (/voluntario/i.test(headerLine) || /\bVOL\b/i.test(headerLine)) {
    result.funds = ['VOL'];
  } else {
    return null;
  }

  // Strategy 1: Try same-line parsing (label + amounts on same line)
  // Strategy 2: Collect standalone amount lines for split-format parsing
  const detectedFieldOrder: string[] = [];
  const standaloneAmounts: number[] = [];

  for (const line of lines) {
    // Check for period
    const periodMatch = line.match(/del\s+(\d{2}\/\d{2}\/\d{4})\s+al\s+(\d{2}\/\d{2}\/\d{4})/i);
    if (periodMatch) {
      result.period_start = parseDateDMY(periodMatch[1]);
      result.period_end = parseDateDMY(periodMatch[2]);
      continue;
    }

    // Check for "Saldo Actual" line (always has amounts inline)
    if (/saldo\s*actual/i.test(line)) {
      const amounts = extractAmounts(line);
      if (amounts.length > 0) {
        result.fields['saldo_final'] = amounts;
      }
      continue;
    }

    // Check if this line matches a field label
    let matchedLabel = false;
    for (const [regex, key] of FIELD_LABELS) {
      if (regex.test(line)) {
        matchedLabel = true;
        const amounts = extractAmounts(line);
        if (amounts.length > 0) {
          // Strategy 1: amounts on same line as label
          result.fields[key] = amounts;
        } else {
          // Strategy 2: label-only line, record the order
          detectedFieldOrder.push(key);
        }
        break;
      }
    }

    // If not a label line, check if it's a standalone amount line
    if (!matchedLabel) {
      const amounts = extractAmounts(line);
      if (amounts.length === 1) {
        standaloneAmounts.push(amounts[0]);
      }
    }
  }

  // If we have standalone amounts and field labels, map them
  // Format: N labels, then N amounts for fund1, then N amounts for fund2, ...
  if (detectedFieldOrder.length > 0 && standaloneAmounts.length > 0) {
    const numFields = detectedFieldOrder.length;
    const numFunds = result.funds.length;

    if (standaloneAmounts.length >= numFields * numFunds) {
      for (let f = 0; f < numFunds; f++) {
        for (let i = 0; i < numFields; i++) {
          const key = detectedFieldOrder[i];
          if (!result.fields[key]) result.fields[key] = [];
          result.fields[key].push(standaloneAmounts[f * numFields + i]);
        }
      }
    }
  }

  return result;
}

export function parsePensionPaste(text: string): PensionParsedEntry[] {
  // Split into blocks by "---" or multiple blank lines
  const blocks = text.split(/(?:^|\n)-{3,}(?:\n|$)|\n{3,}/);
  const entries: PensionParsedEntry[] = [];

  for (const block of blocks) {
    const lines = block.split('\n').filter((l) => l.trim());
    if (lines.length < 3) continue;

    const parsed = parseBlock(lines);
    if (!parsed || !parsed.period_start || !parsed.period_end) continue;

    for (let i = 0; i < parsed.funds.length; i++) {
      const fund = parsed.funds[i];
      const get = (key: string): number => {
        const vals = parsed.fields[key];
        if (!vals) return 0;
        return vals[i] ?? vals[0] ?? 0;
      };

      entries.push({
        fund,
        period_start: parsed.period_start,
        period_end: parsed.period_end,
        saldo_anterior: get('saldo_anterior'),
        aportes: get('aportes'),
        rendimientos: get('rendimientos'),
        retiros: get('retiros'),
        traslados: get('traslados'),
        comision: get('comision'),
        correccion: 0,
        bonificacion: get('bonificacion'),
        saldo_final: get('saldo_final'),
      });
    }
  }

  return entries;
}