<?php
/**
 * controllers/soilImportController.php
 *
 * Handles XLS/XLSX/CSV upload from soil labs, parses the file with
 * PhpSpreadsheet, then uses the local Ollama LLM to map lab-specific
 * column headers to the soil_records database fields.
 *
 * POST /controllers/soilImportController.php
 *   Accepts multipart/form-data with:
 *     file       — the uploaded spreadsheet
 *     action     — "parse"  → return list of samples found in the file
 *                  "import" → return mapped field values for one sample
 *     sample_idx — (import only) 0-based index of the sample to import
 */

require_once __DIR__ . '/../config/database.php';
require_once __DIR__ . '/../config/ai.php';
require_once __DIR__ . '/../lib/auth.php';

if (session_status() === PHP_SESSION_NONE) {
    session_start();
}

requireLogin();

header('Content-Type: application/json');

// ─── helpers ─────────────────────────────────────────────────────────────────

function jsonError(string $message, int $code = 400): never
{
    http_response_code($code);
    echo json_encode(['success' => false, 'error' => $message]);
    exit;
}

function jsonOk(array $data): never
{
    echo json_encode(['success' => true, ...$data]);
    exit;
}

// ─── request validation ───────────────────────────────────────────────────────

if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
    jsonError('Method not allowed', 405);
}

$action = $_POST['action'] ?? 'parse';
if (!in_array($action, ['parse', 'import'], true)) {
    jsonError('Invalid action');
}

// ─── file handling ────────────────────────────────────────────────────────────

if (empty($_FILES['file']) || $_FILES['file']['error'] !== UPLOAD_ERR_OK) {
    jsonError('No file uploaded or upload error: ' . ($_FILES['file']['error'] ?? 'missing'));
}

$uploadedFile = $_FILES['file'];
$ext          = strtolower(pathinfo($uploadedFile['name'], PATHINFO_EXTENSION));

if (!in_array($ext, ['xls', 'xlsx', 'csv', 'ods'], true)) {
    jsonError('Unsupported file type. Please upload XLS, XLSX, CSV, or ODS.');
}

// ─── PhpSpreadsheet ───────────────────────────────────────────────────────────

$autoloadPaths = [
    __DIR__ . '/../vendor/autoload.php',
    __DIR__ . '/../../vendor/autoload.php',
];
$autoloaded = false;
foreach ($autoloadPaths as $path) {
    if (file_exists($path)) {
        require_once $path;
        $autoloaded = true;
        break;
    }
}
if (!$autoloaded) {
    jsonError('PhpSpreadsheet not installed. Run: composer require phpoffice/phpspreadsheet', 500);
}

use PhpOffice\PhpSpreadsheet\IOFactory;
use PhpOffice\PhpSpreadsheet\Spreadsheet;

try {
    $spreadsheet = IOFactory::load($uploadedFile['tmp_name']);
} catch (\Exception $e) {
    jsonError('Could not read file: ' . $e->getMessage());
}

$sheet = $spreadsheet->getActiveSheet();

// Convert sheet to a 2-D array (1-indexed rows and cols → 0-indexed)
$rawData = [];
foreach ($sheet->getRowIterator() as $row) {
    $cells = [];
    foreach ($row->getCellIterator() as $cell) {
        $cells[] = trim((string) $cell->getFormattedValue());
    }
    // Strip trailing empty cells
    while ($cells && end($cells) === '') {
        array_pop($cells);
    }
    if ($cells) {
        $rawData[] = $cells;
    }
}

if (empty($rawData)) {
    jsonError('The spreadsheet appears to be empty.');
}

// ─── format detection ─────────────────────────────────────────────────────────
//
// Two layouts found in CSBP lab files:
//   ROW-BASED    — Row 0 = column headers (LAB_NUMBER, TEXTURE, PH_CACL2 …)
//                  Rows 1-N = one sample per row.
//   TRANSPOSED   — Column 0 = row labels (EC 1:5, Total P % …)
//                  Columns 1-N = one sample per column.
//
// Heuristic: if the first cell of row 0 looks like a short code/identifier
// (< 20 chars, no spaces, all-caps or underscored) → ROW-BASED.
// Otherwise → TRANSPOSED.

function isRowBased(array $rawData): bool
{
    $firstCell = $rawData[0][0] ?? '';
    // Short, code-like headers signal a row-based layout
    return strlen($firstCell) < 25
        && !str_contains($firstCell, ' ')
        && $firstCell !== '';
}

$transposed = !isRowBased($rawData);

// ─── extract samples ──────────────────────────────────────────────────────────
//
// Returns an array of samples, each sample being an assoc array of
// label → value.

function extractSamplesRowBased(array $rawData): array
{
    $headers = $rawData[0];
    $samples = [];
    for ($r = 1; $r < count($rawData); $r++) {
        $row    = $rawData[$r];
        $sample = [];
        foreach ($headers as $c => $header) {
            if ($header === '') {
                continue;
            }
            $sample[$header] = $row[$c] ?? '';
        }
        if (array_filter($sample)) {
            $samples[] = $sample;
        }
    }
    return $samples;
}

function extractSamplesTransposed(array $rawData): array
{
    // Column 0 = labels; columns 1-N = samples
    $labels      = array_column($rawData, 0);
    $numSamples  = max(array_map('count', $rawData)) - 1;
    $samples     = [];

    for ($col = 1; $col <= $numSamples; $col++) {
        $sample = [];
        foreach ($rawData as $rowIdx => $row) {
            $label = $labels[$rowIdx] ?? '';
            $value = $row[$col] ?? '';
            if ($label !== '' && $value !== '') {
                $sample[$label] = $value;
            }
        }
        if (array_filter($sample)) {
            $samples[] = $sample;
        }
    }
    return $samples;
}

$samples = $transposed
    ? extractSamplesTransposed($rawData)
    : extractSamplesRowBased($rawData);

if (empty($samples)) {
    jsonError('No samples found in the file.');
}

// ─── action: parse ────────────────────────────────────────────────────────────
// Return a lightweight list of samples so the UI can let the user pick one.

if ($action === 'parse') {
    $list = [];
    foreach ($samples as $idx => $sample) {
        // Try to find a meaningful display label
        $labId  = $sample['LAB_NUMBER']    ?? $sample['Lab ID (Soil)'] ?? $sample['LAB_ID'] ?? "Sample " . ($idx + 1);
        $client = $sample['CLIENT NAME']   ?? $sample['Consultant']    ?? $sample['CUSTNO']  ?? '';
        $crop   = $sample['CROP']          ?? $sample['Material (manure, sawdust, etc.)'] ?? '';
        $pad    = $sample['PADDOCK']       ?? $sample['Field Name (Sample ID)']            ?? '';

        $list[] = [
            'idx'    => $idx,
            'lab_id' => $labId,
            'client' => $client,
            'crop'   => $crop,
            'site'   => $pad,
        ];
    }
    jsonOk(['samples' => $list, 'count' => count($samples)]);
}

// ─── action: import ───────────────────────────────────────────────────────────

$sampleIdx = (int) ($_POST['sample_idx'] ?? 0);
if ($sampleIdx < 0 || $sampleIdx >= count($samples)) {
    jsonError('Invalid sample index.');
}

$sampleData = $samples[$sampleIdx];

// ─── Ollama field mapping ─────────────────────────────────────────────────────

$labJson = json_encode($sampleData, JSON_UNESCAPED_UNICODE);

$prompt = <<<EOT
You are a soil laboratory data mapper. Your only job is to output a JSON object.

Map the LAB DATA below to these TARGET FIELDS. Output ONLY the JSON object — no explanation, no markdown, no code fences.

TARGET FIELDS:
lab_no=Lab reference number/Lab ID
sample_id=Sample identifier/paddock name/field name
site_id=Site identifier/block/customer number
date_sampled=Date sampled as YYYY-MM-DD
texture=Soil texture description
gravel=Gravel % (number only)
colour=Soil colour
ocarbon=Organic carbon % (number only)
omatter=Organic matter % LOI (number only)
ph_cacl2=pH in CaCl2 (number only)
ph_h2o=pH in water (number only)
ec=Electrical conductivity dS/m (number only)
NO3_N=Nitrate-N mg/kg (number only)
NH3_N=Ammonium-N mg/kg (number only)
p_mehlick=Phosphorus Mehlich-3 mg/kg (number only)
p_morgan=Phosphorus extractable mg/kg (number only)
k_morgan=Potassium mg/kg (number only)
ca_morgan=Calcium mg/kg (number only)
mg_morgan=Magnesium mg/kg (number only)
na_morgan=Sodium mg/kg (number only)
s_morgan=Sulphur mg/kg (number only)
b_cacl2=Boron CaCl2 mg/kg (number only)
mn_dtpa=Manganese DTPA mg/kg (number only)
zn_dtpa=Zinc DTPA mg/kg (number only)
fe_dtpa=Iron DTPA mg/kg (number only)
cu_dtpa=Copper DTPA mg/kg (number only)
al=Aluminium mg/kg (number only)
tec=Total Exchange Capacity (number only)
cec=CEC meq/100g (number only)
ca_mehlick3=Calcium Mehlich-3 meq/100g (number only)
mg_mehlick3=Magnesium Mehlich-3 meq/100g (number only)
k_mehlick3=Potassium Mehlich-3 meq/100g (number only)
na_mehlick3=Sodium Mehlich-3 meq/100g (number only)
al_mehlick3=Aluminium Mehlich-3 meq/100g (number only)

LAB DATA: {$labJson}

Rules: only use values present in the lab data. Strip units from numbers. Use null for unmapped fields. Output JSON only.
EOT;

$payload = json_encode([
    'model'  => OLLAMA_MODEL,
    'prompt' => $prompt,
    'stream' => false,
    'options' => [
        'temperature' => OLLAMA_TEMPERATURE,
        'num_predict' => 1024,
    ],
]);

$ch = curl_init(OLLAMA_HOST . '/api/generate');
curl_setopt_array($ch, [
    CURLOPT_POST           => true,
    CURLOPT_POSTFIELDS     => $payload,
    CURLOPT_HTTPHEADER     => ['Content-Type: application/json'],
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_TIMEOUT        => OLLAMA_TIMEOUT,
    CURLOPT_CONNECTTIMEOUT => 5,
]);

$response = curl_exec($ch);
$httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
$curlErr  = curl_error($ch);
curl_close($ch);

if ($curlErr || $httpCode !== 200) {
    $mapped = staticFieldMap($sampleData);
    $warning = $curlErr ?: "Ollama HTTP {$httpCode}";
    jsonOk(['fields' => $mapped, 'method' => 'static', 'warning' => 'AI unavailable: ' . $warning]);
}

$ollamaData = json_decode($response, true);
$rawText    = trim($ollamaData['response'] ?? '');

if ($rawText === '') {
    $mapped = staticFieldMap($sampleData);
    jsonOk(['fields' => $mapped, 'method' => 'static', 'warning' => 'Ollama returned empty response']);
}

// Strip any markdown code fences the model might wrap around the JSON
$rawText = preg_replace('/^```(?:json)?\s*/i', '', $rawText);
$rawText = preg_replace('/\s*```$/m', '', $rawText);
// Extract the first JSON object if the model added commentary
if (preg_match('/\{[\s\S]+\}/', $rawText, $m)) {
    $rawText = $m[0];
}

$mapped = json_decode($rawText, true);

if (!is_array($mapped)) {
    $mapped = staticFieldMap($sampleData);
    jsonOk(['fields' => $mapped, 'method' => 'static', 'warning' => 'AI returned unparseable JSON']);
}

// Remove null/empty values
$mapped = array_filter($mapped, fn($v) => $v !== null && $v !== '');

jsonOk(['fields' => $mapped, 'method' => 'ai']);

// ─── static fallback mapper ───────────────────────────────────────────────────
// Simple keyword-based mapping used when the AI is unavailable.

function staticFieldMap(array $data): array
{
    $map = [
        // lab_no
        'lab_no'      => ['LAB_NUMBER', 'Lab ID (Soil)', 'LAB_ID'],
        // sample / site
        'sample_id'   => ['PADDOCK', 'Field Name (Sample ID)', 'PADDOCK_NAME'],
        'site_id'     => ['CUSTNO', 'Lab performing testing'],
        // physical
        'texture'     => ['TEXTURE'],
        'gravel'      => ['GRAVEL'],
        'colour'      => ['COLOUR', 'COLOR'],
        // chemical
        'ocarbon'     => ['ORGCARBON', 'Organic Carbon %', 'Total Organic Carbon %'],
        'omatter'     => ['Total Organic Matter (L.O.I) %', 'Organic Matter %'],
        'ph_cacl2'    => ['PH_CACL2', 'PH 1:5 (CaCl2)', 'pH CaCl2', 'ph_cacl2'],
        'ph_h2o'      => ['PH_H2O', 'pH 1:5 (H2O)', 'pH Water'],
        'ec'          => ['CONDUCTY', 'EC 1:5', 'EC'],
        // nutrients
        'NO3_N'       => ['NITRATE', 'Nitrate ppm', 'Nitrate-N', 'NO3_N'],
        'NH3_N'       => ['NAMMONIUM', 'Ammonium', 'NH4_N'],
        'p_morgan'    => ['PHOS', 'Total P %', 'Phosphorus'],
        'k_morgan'    => ['POTASSIUM', 'Total K %', 'Potassium'],
        'ca_morgan'   => ['EXC_CA', 'Total Ca %', 'Calcium'],
        'mg_morgan'   => ['EXC_MG', 'Total Mg %', 'Magnesium'],
        'na_morgan'   => ['EXC_NA', 'Total Na %', 'Sodium'],
        's_morgan'    => ['SULPHUR', 'Total S %', 'Sulphur'],
        // micronutrients
        'b_cacl2'     => ['BORON_HOT', 'Total B ppm', 'Boron'],
        'mn_dtpa'     => ['DTPA_MN', 'EDTA_MN', 'Total Mn ppm', 'Manganese'],
        'zn_dtpa'     => ['DTPA_ZN', 'EDTA_ZN', 'Total Zn ppm', 'Zinc'],
        'fe_dtpa'     => ['DTPA_FE', 'EDTA_FE', 'Total Fe ppm', 'Iron', 'IRON'],
        'cu_dtpa'     => ['DTPA_CU', 'EDTA_CU', 'Total Cu ppm', 'Copper'],
        'al'          => ['ALUM_CACL2', 'EXC_AL', 'Aluminium'],
        // base saturation
        'cec'         => ['CEC', 'COND', 'SAT_COND'],
        'ca_mehlick3' => ['SAT_Ca', 'SAT_CA'],
        'mg_mehlick3' => ['SAT_Mg', 'SAT_MG'],
        'k_mehlick3'  => ['SAT_K'],
        'na_mehlick3' => ['SAT_Na', 'SAT_NA'],
    ];

    $result = [];
    foreach ($map as $dbField => $labKeys) {
        foreach ($labKeys as $labKey) {
            // Case-insensitive search
            foreach ($data as $k => $v) {
                if (strcasecmp($k, $labKey) === 0 && $v !== '') {
                    $result[$dbField] = $v;
                    break 2;
                }
            }
        }
    }
    return $result;
}