export default function parseAbsence(str, teacherMap) {
  str = str.trim().replace(/\s+/g, " ");

  const result = {
    teacher: null,
    teacherCode: null,
    type: null, // "wholeDay" | "range" | "single" | "invalid"
    hours: null
  };

  // Patterns (teacher can be before or after the hours)
  const wholeDayPattern = /^([A-Za-z]+)$/;
  const rangePattern = /^(\d+)\s*-\s*(\d+)\s+([A-Za-z]+)$|^([A-Za-z]+)\s+(\d+)\s*-\s*(\d+)$/;
  const singleHourPattern = /^(\d+)\s+([A-Za-z]+)$|^([A-Za-z]+)\s+(\d+)$/;
  const plusPattern = /^(\d+)\+\s+([A-Za-z]+)$|^([A-Za-z]+)\s+(\d+)\+$/;

  if (rangePattern.test(str)) {
    const match = str.match(rangePattern);
    // Case 1: hours first, then teacher
    if (match[1] && match[2] && match[3]) {
      const [, from, to, teacherCode] = match;
      result.teacherCode = teacherCode;
      result.teacher = teacherMap[teacherCode.toLowerCase()];
      result.type = "range";
      result.hours = { from: parseInt(from), to: parseInt(to) };
    }
    // Case 2: teacher first, then hours
    else {
      const [, , , teacherCode, from, to] = match;
      result.teacherCode = teacherCode;
      result.teacher = teacherMap[teacherCode.toLowerCase()];
      result.type = "range";
      result.hours = { from: parseInt(from), to: parseInt(to) };
    }
  }
  else if (plusPattern.test(str)) {
    const match = str.match(plusPattern);
    if (match[1] && match[2]) {
      // hours first
      const [, from, teacherCode] = match;
      result.teacherCode = teacherCode;
      result.teacher = teacherMap[teacherCode.toLowerCase()];
      result.type = "range";
      result.hours = { from: parseInt(from), to: 10 };
    } else {
      // teacher first
      const [, , teacherCode, from] = match;
      result.teacherCode = teacherCode;
      result.teacher = teacherMap[teacherCode.toLowerCase()];
      result.type = "range";
      result.hours = { from: parseInt(from), to: 10 };
    }
  }
  else if (singleHourPattern.test(str)) {
    const match = str.match(singleHourPattern);
    if (match[1] && match[2]) {
      // hours first
      const [, hour, teacherCode] = match;
      result.teacherCode = teacherCode;
      result.teacher = teacherMap[teacherCode.toLowerCase()];
      result.type = "single";
      result.hours = parseInt(hour);
    } else {
      // teacher first
      const [, , teacherCode, hour] = match;
      result.teacherCode = teacherCode;
      result.teacher = teacherMap[teacherCode.toLowerCase()];
      result.type = "single";
      result.hours = parseInt(hour);
    }
  }
  else if (wholeDayPattern.test(str)) {
    const [, teacherCode] = str.match(wholeDayPattern);
    result.teacher = teacherMap[teacherCode.toLowerCase()];
    result.teacherCode = teacherCode;
    result.type = "wholeDay";
  }
  else {
    result.type = "invalid";
    result.original = str;
  }

  return result;
}