<?php
/**
 * WEVAL Feature Adoption Tracker sovereign 21avr2026
 * Track which modules/widgets/features users interact with per session
 * Storage: /opt/weval-l99/data/feature-adoption.jsonl
 * 
 * GET  ?action=stats   -> adoption rate KPI
 * POST ?action=track   -> log feature use (feature, user, session_id)
 * GET  ?action=list    -> features inventory
 */
header("Content-Type: application/json");
header("Access-Control-Allow-Origin: *");

$STORAGE = "/opt/weval-l99/data/feature-adoption.jsonl";
$INVENTORY = "/opt/weval-l99/data/feature-inventory.json";
@mkdir(dirname($STORAGE), 0755, true);

// Default inventory if not exists
if (!file_exists($INVENTORY)) {
    $default_features = [
        "wtp_dashboard", "wtp_pilotage_widget", "wtp_sparklines", "wtp_l99_brain",
        "wevia_master_chat", "wevia_orchestrator", "all_ia_hub", "agents_archi",
        "architecture_live", "openclaw", "nonreg_dashboard", "stripe_live",
        "ethica_hcp", "wevads_ia", "director_chat", "orphans_hub",
        "wikidoc", "vault_manager", "nps_feedback", "csat_rating", "ticket_create"
    ];
    @file_put_contents($INVENTORY, json_encode(["features" => $default_features, "total" => count($default_features)]));
}

$action = $_GET["action"] ?? ($_POST["action"] ?? "stats");

if ($action === "track" && $_SERVER["REQUEST_METHOD"] === "POST") {
    $feature = substr(trim($_POST["feature"] ?? ""), 0, 80);
    $user = substr(trim($_POST["user"] ?? "anonymous"), 0, 60);
    $session = substr(trim($_POST["session_id"] ?? ""), 0, 40);
    if (!$feature) {
        echo json_encode(["ok"=>false,"error"=>"feature_required"]);
        exit;
    }
    $record = ["ts"=>date("c"),"feature"=>$feature,"user"=>$user,"session_id"=>$session];
    @file_put_contents($STORAGE, json_encode($record)."\n", FILE_APPEND | LOCK_EX);
    echo json_encode(["ok"=>true,"tracked"=>$feature]);
    exit;
}

if ($action === "list") {
    $inv = @json_decode(@file_get_contents($INVENTORY), true);
    echo json_encode($inv ?: ["features"=>[],"total"=>0]);
    exit;
}

// stats = adoption rate calculation
$inv = @json_decode(@file_get_contents($INVENTORY), true);
$total_features = intval($inv["total"] ?? 0);

$used_features = [];
$events = [];
if (is_readable($STORAGE)) {
    foreach (file($STORAGE) as $line) {
        $r = @json_decode(trim($line), true);
        if ($r && isset($r["feature"])) {
            $used_features[$r["feature"]] = ($used_features[$r["feature"]] ?? 0) + 1;
            $events[] = $r;
        }
    }
}

$adopted = count($used_features);
$adoption_rate = $total_features > 0 ? round(($adopted / $total_features) * 100) : 0;

// 7d & 30d activity
$now = time();
$evt_7d = 0; $evt_30d = 0;
$users_7d = []; $users_30d = [];
foreach ($events as $e) {
    $t = strtotime($e["ts"]);
    if ($t >= $now - 7*86400)  { $evt_7d++;  $users_7d[$e["user"] ?? ""] = true; }
    if ($t >= $now - 30*86400) { $evt_30d++; $users_30d[$e["user"] ?? ""] = true; }
}

echo json_encode([
    "ok"=>true,
    "source"=>"sovereign_jsonl_tracker",
    "ts"=>date("c"),
    "adoption_rate_pct"=>$adoption_rate,
    "features_total"=>$total_features,
    "features_adopted"=>$adopted,
    "features_top5"=>array_slice(array_reverse(array_keys($used_features)), 0, 5),
    "events_total"=>count($events),
    "events_7d"=>$evt_7d,
    "events_30d"=>$evt_30d,
    "unique_users_7d"=>count($users_7d),
    "unique_users_30d"=>count($users_30d),
    "status"=>count($events)===0 ? "wire_needed" : ($adoption_rate >= 70 ? "ok" : "warn"),
    "drill"=>"Features used / Features available · Track via POST ?action=track",
]);