/**
 * TGICS patient questionnaire — stable codes + branching rules.
 */

const opt = (value, label) => ({ value, label });

const QUESTIONS = {
  gender: {
    code: 'gender',
    label: 'Gender',
    type: 'single',
    required: true,
    options: [
      opt('male', 'Male'),
      opt('female', 'Female'),
      opt('prefer_not_to_say', 'Prefer not to say'),
    ],
  },
  patient_age: {
    code: 'patient_age',
    label: 'Age (in completed years)',
    type: 'number',
    required: true,
    min: 0,
    max: 120,
  },
  exposure_history: {
    code: 'exposure_history',
    label: 'History of exposure?',
    type: 'multi',
    required: true,
    options: [
      opt('never_smoker', 'Never smoker'),
      opt('ex_smoker', 'Ex-smoker'),
      opt('current_smoker', 'Current smoker'),
      opt('pulmonary_tb_contact', 'Suffered or ever came in contact with a patient who had Pulmonary TB'),
      opt('indoor_air_pollution', 'Current exposure to any sources of Indoor Air Pollution (eg: Incense Sticks, Mosquito Coil, Loban, Dhoop, Smoke from Tandoor/ cooking, Smoker in the family, fungus on walls (grey-black patches on wall))'),
    ],
  },
  occupation_exposure: {
    code: 'occupation_exposure',
    label: 'Work/occupation exposed to',
    type: 'multi',
    required: true,
    options: [
      opt('smoke', 'Smoke'),
      opt('fumes', 'Fumes'),
      opt('dust', 'Dust'),
      opt('gases', 'Gases'),
      opt('none', 'None'),
    ],
  },
  family_history: {
    code: 'family_history',
    label: 'Family history',
    type: 'multi',
    required: true,
    options: [
      opt('allergic_dermatitis_rhinitis_migraine', 'Allergic Dermatitis, Allergic Rhinitis, Migraine'),
      opt('asthma', 'Asthma'),
      opt('gerd', 'GERD (Gastroesophageal Reflux Disease)'),
      opt('tb', 'TB'),
      opt('rheumatic', 'Rheumatic diseases (arthritis, heart disease)'),
      opt('cardiovascular', 'Cardiovascular diseases'),
      opt('no_specific', 'No specific'),
    ],
  },
  past_disease_history: {
    code: 'past_disease_history',
    label: 'Past disease history of patient',
    type: 'multi',
    required: true,
    options: [
      opt('allergic_dermatitis_rhinitis_migraine', 'Allergic Dermatitis, Allergic Rhinitis, Migraine'),
      opt('asthma', 'Asthma'),
      opt('copd', 'COPD'),
      opt('tb', 'TB'),
      opt('sinus_issues', 'Sinus issues (Post Nasal Drip)'),
      opt('gerd', 'GERD (Gastroesophageal Reflux Disease)'),
      opt('rheumatic', 'Rheumatic diseases (arthritis, heart disease)'),
      opt('other_lung_disease', 'Any other lung disease'),
      opt('no_history', 'No history of any disease'),
    ],
  },
  organ_system: {
    code: 'organ_system',
    label: 'What organ/system is involved for which the patient is visiting the doctor today?',
    type: 'multi',
    required: true,
    options: [
      opt('skin', 'Skin'),
      opt('brain_spinal', 'Brain & spinal cord'),
      opt('ent', 'Ear/Nose/Throat'),
      opt('heart', 'Heart disease'),
      opt('lungs', 'Lungs & breathing tubes'),
      opt('abdomen', 'Abdomen'),
      opt('kidney', 'Kidney'),
      opt('pregnancy_reproductive', 'Pregnancy & reproductive issues'),
      opt('muscles_bones_joints', 'Muscles/Bones/Joints'),
    ],
  },
  ailment: {
    code: 'ailment',
    label: 'For which ailment is the patient visiting the Doctor today?',
    type: 'multi',
    required: true,
    options: [
      opt('fever', 'Fever'),
      opt('high_bp', 'High blood pressure'),
      opt('diabetes', 'Diabetes'),
      opt('anaemia', 'Anaemia'),
      opt('stomach_upset', 'Stomach upset (vomiting / loose motions)'),
      opt('cold_throat', 'Cold (runny nose) &/or throat irritation/pain'),
      opt('thyroid', 'Thyroid'),
      opt('rashes', 'Rashes (any where)'),
      opt('swelling', 'Swelling on feet / body'),
      opt('breathlessness', 'Breathlessness'),
      opt('backache_weakness', 'Back ache / Weakness / Joint pain / Body ache'),
      opt('foreign_body', 'Foreign body in eye/ear/nose/throat'),
      opt('physical_injury', 'Physical injury'),
      opt('others', 'Others (please specify briefly)'),
    ],
    otherField: 'ailment_other',
  },
  has_cough: {
    code: 'has_cough',
    label: 'Does the patient complain of cough?',
    type: 'single',
    required: true,
    options: [opt('yes', 'Yes'), opt('no', 'No')],
  },
  cough_duration: {
    code: 'cough_duration',
    label: 'What is the duration of cough?',
    type: 'single',
    required: true,
    options: [
      opt('lt_7_days', 'Less than 7 days'),
      opt('7_days_to_3_weeks', '7 days to <3 weeks'),
      opt('3_weeks_to_2_months', '3 weeks to 2 months'),
      opt('gt_2_months', 'More than 2 months'),
    ],
  },
  cough_type: {
    code: 'cough_type',
    label: 'Is the cough dry or wet (does the patient expel out sputum/mucus/phlegm during coughing)?',
    type: 'single',
    required: true,
    options: [
      opt('dry', 'Dry'),
      opt('wet', 'Wet (with sputum/mucus/phlegm)'),
    ],
  },
  sputum_quantity: {
    code: 'sputum_quantity',
    label: 'How much is the quantity of sputum/mucus/phlegm?',
    type: 'single',
    required: true,
    options: [
      opt('scanty', 'Scanty (very less sputum/mucus/phlegm production/expulsion even after coughing)'),
      opt('moderate', 'Moderate (some amount of sputum/mucus/phlegm production/expulsion after coughing)'),
      opt('excess', 'Excess (too much sputum/mucus/phlegm production/expulsion even with or without cough)'),
      opt('sometimes_excess_sometimes_less', 'Sometimes excess and sometimes less'),
      opt('more_early_morning', 'More in early morning'),
    ],
  },
  sputum_colour: {
    code: 'sputum_colour',
    label: 'What is the colour of the sputum/mucus/phlegm?',
    type: 'single',
    required: true,
    options: [
      opt('white', 'White'),
      opt('yellow', 'Yellow'),
      opt('green', 'Green'),
      opt('brownish', 'Brownish'),
      opt('pink', 'Pink'),
      opt('blood_tinged', 'Blood tinged'),
    ],
  },
  cough_associated: {
    code: 'cough_associated',
    label: 'Is cough associated with?',
    type: 'multi',
    required: true,
    options: [
      opt('fever', 'Fever'),
      opt('weight_loss', 'Weight loss'),
      opt('loss_of_appetite', 'Loss of appetite'),
      opt('evening_rise_fever', 'Evening rise of fever'),
      opt('difficulty_breathing', 'Difficulty in breathing'),
      opt('wheeze', 'Whistling sound from chest/ wheeze'),
      opt('chest_pain', 'Chest pain'),
      opt('hoarseness', 'Hoarseness of voice'),
      opt('sinusitis', 'Sinusitis (Post Nasal Drip)'),
      opt('acid_reflux', 'Acid Reflux/Regurgitation'),
      opt('night_sweats', 'Night sweats'),
      opt('others', 'Others (please specify)'),
      opt('none', 'None of the above'),
    ],
    otherField: 'cough_associated_other',
  },
  cough_diagnosis: {
    code: 'cough_diagnosis',
    label: 'What is the diagnosis for cough?',
    type: 'single',
    required: true,
    options: [
      opt('common_cold', 'Common cold'),
      opt('sinusitis', 'Sinusitis'),
      opt('allergic_cough', 'Allergic Cough'),
      opt('allergic_rhinitis', 'Allergic Rhinitis'),
      opt('asthma', 'Asthma'),
      opt('drug_induced', 'Drug induced cough'),
      opt('acidity_gerd', 'Acidity induced cough (GERD)'),
      opt('post_nasal_drip', 'Post Nasal Drip (Upper Airway Cough Syndrome)'),
      opt('tb', 'TB'),
      opt('copd', 'COPD'),
      opt('others', 'Others (please specify)'),
      opt('not_sure', 'Not sure of diagnosis'),
    ],
    otherField: 'cough_diagnosis_other',
  },
};

function optionValues(question) {
  return new Set(question.options.map((o) => o.value));
}

function validateAnswers(answers) {
  if (!answers || typeof answers !== 'object') {
    return { ok: false, message: 'Answers are required.' };
  }

  const requireSingle = (code) => {
    const q = QUESTIONS[code];
    const val = answers[code];
    if (val === undefined || val === null || val === '') {
      return `${q.label} is required.`;
    }
    if (!optionValues(q).has(String(val))) {
      return `Invalid value for ${q.label}.`;
    }
    return null;
  };

  const requireMulti = (code) => {
    const q = QUESTIONS[code];
    const val = answers[code];
    if (!Array.isArray(val) || val.length === 0) {
      return `${q.label} is required.`;
    }
    const allowed = optionValues(q);
    for (const v of val) {
      if (!allowed.has(String(v))) {
        return `Invalid value for ${q.label}.`;
      }
    }
    return null;
  };

  const requireOther = (code) => {
    const q = QUESTIONS[code];
    if (!q.otherField) return null;
    const val = answers[code];
    const selected = Array.isArray(val) ? val : [val];
    if (selected.includes('others')) {
      const other = String(answers[q.otherField] || '').trim();
      if (!other) {
        return `Please specify details for ${q.label}.`;
      }
    }
    return null;
  };

  let err =
    requireSingle('gender') ||
    null;
  if (err) return { ok: false, message: err };

  const age = Number(answers.patient_age);
  if (!Number.isFinite(age) || age < 0 || age > 120) {
    return { ok: false, message: 'Valid patient age is required (0–120).' };
  }

  for (const code of [
    'exposure_history',
    'occupation_exposure',
    'family_history',
    'past_disease_history',
    'organ_system',
    'ailment',
  ]) {
    err = requireMulti(code) || requireOther(code);
    if (err) return { ok: false, message: err };
  }

  err = requireSingle('has_cough');
  if (err) return { ok: false, message: err };

  const hasCough = String(answers.has_cough) === 'yes';
  if (!hasCough) {
    return { ok: true, hasCough: false };
  }

  err =
    requireSingle('cough_duration') ||
    requireSingle('cough_type');
  if (err) return { ok: false, message: err };

  const isWet = String(answers.cough_type) === 'wet';
  if (isWet) {
    err =
      requireSingle('sputum_quantity') ||
      requireSingle('sputum_colour');
    if (err) return { ok: false, message: err };
  }

  err =
    requireMulti('cough_associated') ||
    requireOther('cough_associated') ||
    requireSingle('cough_diagnosis') ||
    requireOther('cough_diagnosis');
  if (err) return { ok: false, message: err };

  return { ok: true, hasCough: true };
}

module.exports = {
  QUESTIONS,
  validateAnswers,
};