<?php
/**
 * ISEC (Indian Socio Economic Classification) Helper
 * Based on MRSI's official ISEC grid (updated March 2024)
 * 
 * Computes ISEC tier (G1-G12) from 3 inputs:
 * - Occupation of Chief Wage Earner
 * - Education of Highest Educated Male Adult (21+)
 * - Education of Highest Educated Female Adult (21+)
 */

/**
 * ISEC Classification Grid
 * Structure: $grid[occupation][male_education][female_education] = tier (1-12)
 * 
 * Occupation codes: labour, farmer, worker, trader, clerical, managerial
 * Education codes: no_adult, no_formal, upto_5, class_6_9, class_10_14, degree_regular, degree_professional
 */
function getISECGrid() {
    return [
        'labour' => [
            'no_adult'           => ['no_adult'=>12,'no_formal'=>12,'upto_5'=>11,'class_6_9'=>11,'class_10_14'=>10,'degree_regular'=>9,'degree_professional'=>9],
            'no_formal'          => ['no_adult'=>12,'no_formal'=>12,'upto_5'=>11,'class_6_9'=>11,'class_10_14'=>11,'degree_regular'=>10,'degree_professional'=>10],
            'upto_5'             => ['no_adult'=>12,'no_formal'=>12,'upto_5'=>11,'class_6_9'=>11,'class_10_14'=>10,'degree_regular'=>9,'degree_professional'=>9],
            'class_6_9'          => ['no_adult'=>12,'no_formal'=>11,'upto_5'=>11,'class_6_9'=>10,'class_10_14'=>10,'degree_regular'=>9,'degree_professional'=>9],
            'class_10_14'        => ['no_adult'=>11,'no_formal'=>11,'upto_5'=>10,'class_6_9'=>10,'class_10_14'=>9,'degree_regular'=>8,'degree_professional'=>7],
            'degree_regular'     => ['no_adult'=>9,'no_formal'=>10,'upto_5'=>9,'class_6_9'=>9,'class_10_14'=>8,'degree_regular'=>7,'degree_professional'=>6],
            'degree_professional'=> ['no_adult'=>9,'no_formal'=>10,'upto_5'=>9,'class_6_9'=>8,'class_10_14'=>7,'degree_regular'=>6,'degree_professional'=>6],
        ],
        'farmer' => [
            'no_adult'           => ['no_adult'=>12,'no_formal'=>12,'upto_5'=>11,'class_6_9'=>11,'class_10_14'=>10,'degree_regular'=>9,'degree_professional'=>9],
            'no_formal'          => ['no_adult'=>12,'no_formal'=>12,'upto_5'=>11,'class_6_9'=>11,'class_10_14'=>11,'degree_regular'=>10,'degree_professional'=>10],
            'upto_5'             => ['no_adult'=>12,'no_formal'=>12,'upto_5'=>11,'class_6_9'=>11,'class_10_14'=>10,'degree_regular'=>9,'degree_professional'=>9],
            'class_6_9'          => ['no_adult'=>12,'no_formal'=>11,'upto_5'=>11,'class_6_9'=>10,'class_10_14'=>10,'degree_regular'=>9,'degree_professional'=>9],
            'class_10_14'        => ['no_adult'=>11,'no_formal'=>11,'upto_5'=>10,'class_6_9'=>10,'class_10_14'=>9,'degree_regular'=>8,'degree_professional'=>7],
            'degree_regular'     => ['no_adult'=>9,'no_formal'=>10,'upto_5'=>9,'class_6_9'=>9,'class_10_14'=>8,'degree_regular'=>7,'degree_professional'=>6],
            'degree_professional'=> ['no_adult'=>9,'no_formal'=>10,'upto_5'=>9,'class_6_9'=>8,'class_10_14'=>7,'degree_regular'=>6,'degree_professional'=>5],
        ],
        'worker' => [
            'no_adult'           => ['no_adult'=>12,'no_formal'=>12,'upto_5'=>11,'class_6_9'=>10,'class_10_14'=>10,'degree_regular'=>8,'degree_professional'=>8],
            'no_formal'          => ['no_adult'=>11,'no_formal'=>11,'upto_5'=>11,'class_6_9'=>11,'class_10_14'=>10,'degree_regular'=>9,'degree_professional'=>8],
            'upto_5'             => ['no_adult'=>11,'no_formal'=>11,'upto_5'=>10,'class_6_9'=>10,'class_10_14'=>10,'degree_regular'=>9,'degree_professional'=>7],
            'class_6_9'          => ['no_adult'=>11,'no_formal'=>11,'upto_5'=>10,'class_6_9'=>9,'class_10_14'=>9,'degree_regular'=>8,'degree_professional'=>7],
            'class_10_14'        => ['no_adult'=>10,'no_formal'=>10,'upto_5'=>9,'class_6_9'=>9,'class_10_14'=>8,'degree_regular'=>6,'degree_professional'=>6],
            'degree_regular'     => ['no_adult'=>8,'no_formal'=>9,'upto_5'=>8,'class_6_9'=>8,'class_10_14'=>7,'degree_regular'=>5,'degree_professional'=>4],
            'degree_professional'=> ['no_adult'=>8,'no_formal'=>9,'upto_5'=>7,'class_6_9'=>7,'class_10_14'=>5,'degree_regular'=>3,'degree_professional'=>3],
        ],
        'trader' => [
            'no_adult'           => ['no_adult'=>11,'no_formal'=>12,'upto_5'=>11,'class_6_9'=>10,'class_10_14'=>9,'degree_regular'=>6,'degree_professional'=>5],
            'no_formal'          => ['no_adult'=>11,'no_formal'=>11,'upto_5'=>11,'class_6_9'=>10,'class_10_14'=>9,'degree_regular'=>8,'degree_professional'=>8],
            'upto_5'             => ['no_adult'=>11,'no_formal'=>11,'upto_5'=>10,'class_6_9'=>9,'class_10_14'=>8,'degree_regular'=>8,'degree_professional'=>7],
            'class_6_9'          => ['no_adult'=>10,'no_formal'=>11,'upto_5'=>10,'class_6_9'=>9,'class_10_14'=>8,'degree_regular'=>7,'degree_professional'=>5],
            'class_10_14'        => ['no_adult'=>9,'no_formal'=>10,'upto_5'=>9,'class_6_9'=>8,'class_10_14'=>7,'degree_regular'=>5,'degree_professional'=>4],
            'degree_regular'     => ['no_adult'=>7,'no_formal'=>9,'upto_5'=>8,'class_6_9'=>7,'class_10_14'=>6,'degree_regular'=>3,'degree_professional'=>2],
            'degree_professional'=> ['no_adult'=>6,'no_formal'=>8,'upto_5'=>6,'class_6_9'=>6,'class_10_14'=>4,'degree_regular'=>2,'degree_professional'=>2],
        ],
        'clerical' => [
            'no_adult'           => ['no_adult'=>10,'no_formal'=>12,'upto_5'=>10,'class_6_9'=>10,'class_10_14'=>8,'degree_regular'=>7,'degree_professional'=>6],
            'no_formal'          => ['no_adult'=>11,'no_formal'=>11,'upto_5'=>10,'class_6_9'=>10,'class_10_14'=>10,'degree_regular'=>9,'degree_professional'=>8],
            'upto_5'             => ['no_adult'=>11,'no_formal'=>11,'upto_5'=>10,'class_6_9'=>9,'class_10_14'=>8,'degree_regular'=>7,'degree_professional'=>7],
            'class_6_9'          => ['no_adult'=>10,'no_formal'=>10,'upto_5'=>9,'class_6_9'=>9,'class_10_14'=>8,'degree_regular'=>7,'degree_professional'=>6],
            'class_10_14'        => ['no_adult'=>8,'no_formal'=>9,'upto_5'=>8,'class_6_9'=>8,'class_10_14'=>7,'degree_regular'=>6,'degree_professional'=>4],
            'degree_regular'     => ['no_adult'=>7,'no_formal'=>9,'upto_5'=>8,'class_6_9'=>7,'class_10_14'=>6,'degree_regular'=>4,'degree_professional'=>3],
            'degree_professional'=> ['no_adult'=>6,'no_formal'=>8,'upto_5'=>7,'class_6_9'=>6,'class_10_14'=>4,'degree_regular'=>2,'degree_professional'=>2],
        ],
        'managerial' => [
            'no_adult'           => ['no_adult'=>10,'no_formal'=>12,'upto_5'=>10,'class_6_9'=>10,'class_10_14'=>7,'degree_regular'=>5,'degree_professional'=>5],
            'no_formal'          => ['no_adult'=>11,'no_formal'=>11,'upto_5'=>10,'class_6_9'=>10,'class_10_14'=>10,'degree_regular'=>8,'degree_professional'=>6],
            'upto_5'             => ['no_adult'=>11,'no_formal'=>11,'upto_5'=>10,'class_6_9'=>9,'class_10_14'=>8,'degree_regular'=>6,'degree_professional'=>6],
            'class_6_9'          => ['no_adult'=>9,'no_formal'=>9,'upto_5'=>9,'class_6_9'=>8,'class_10_14'=>7,'degree_regular'=>6,'degree_professional'=>6],
            'class_10_14'        => ['no_adult'=>7,'no_formal'=>9,'upto_5'=>8,'class_6_9'=>7,'class_10_14'=>5,'degree_regular'=>3,'degree_professional'=>3],
            'degree_regular'     => ['no_adult'=>6,'no_formal'=>8,'upto_5'=>7,'class_6_9'=>6,'class_10_14'=>4,'degree_regular'=>2,'degree_professional'=>1],
            'degree_professional'=> ['no_adult'=>5,'no_formal'=>7,'upto_5'=>6,'class_6_9'=>5,'class_10_14'=>3,'degree_regular'=>1,'degree_professional'=>1],
        ],
    ];
}

/**
 * Compute ISEC tier from the 3 profiler responses
 * 
 * @param string $occupation - Occupation code of CWE
 * @param string $maleEducation - Education code of highest educated male adult
 * @param string $femaleEducation - Education code of highest educated female adult
 * @return int|null - ISEC tier (1-12) or null if cannot compute
 */
function computeISECTier($occupation, $maleEducation, $femaleEducation) {
    $grid = getISECGrid();
    
    if (isset($grid[$occupation][$maleEducation][$femaleEducation])) {
        return $grid[$occupation][$maleEducation][$femaleEducation];
    }
    
    return null;
}

/**
 * Get SEC class label from ISEC tier
 * 
 * @param int $tier - ISEC tier (1-12)
 * @return string - SEC class (A/B/C/D/E) with description
 */
function getISECClass($tier) {
    if ($tier >= 1 && $tier <= 6)  return 'A';
    if ($tier >= 7 && $tier <= 8)  return 'B';
    if ($tier >= 9 && $tier <= 10) return 'C';
    if ($tier == 11)               return 'D';
    if ($tier == 12)               return 'E';
    return null;
}

/**
 * Get full SEC class label with description
 */
function getISECClassLabel($tier) {
    $labels = [
        'A' => 'SEC A — High',
        'B' => 'SEC B — Upper Middle',
        'C' => 'SEC C — Middle',
        'D' => 'SEC D — Lower Middle',
        'E' => 'SEC E — Low',
    ];
    $class = getISECClass($tier);
    return $class ? $labels[$class] : null;
}