Update: 2026-05-08 00:26:39

app/Core/AiUsageLogger.php

@@ -0,0 +1,102 @@
+<?php
+/**
+ * AI Usage Logger Service
+ * Records every AI API call with token counts and estimated cost.
+ */
+
+namespace App\Core;
+
+class AiUsageLogger
+{
+    /**
+     * Cost per 1M tokens (input/output) for each model.
+     * Update these when pricing changes.
+     */
+    private const MODEL_PRICING = [
+        'gemini-1.5-flash' => [
+            'input'  => 0.075,   // $0.075 per 1M input tokens
+            'output' => 0.30,    // $0.30 per 1M output tokens
+        ],
+        'gemini-2.0-flash' => [
+            'input'  => 0.10,
+            'output' => 0.40,
+        ],
+        'gemini-1.5-pro' => [
+            'input'  => 1.25,
+            'output' => 5.00,
+        ],
+        'grok-2' => [
+            'input'  => 2.00,
+            'output' => 10.00,
+        ],
+        'whisper-large-v3' => [
+            'input'  => 0.111,   // $0.111 per 1M input tokens (Groq)
+            'output' => 0.0,
+        ],
+    ];
+
+    /**
+     * Log an AI usage event.
+     *
+     * @param string      $tenantId
+     * @param string      $actionType  One of: invoice_extraction, voice_transcribe, voice_intent, report_generation, chatbot
+     * @param string      $modelName   e.g. gemini-1.5-flash
+     * @param int         $promptTokens
+     * @param int         $completionTokens
+     * @param string|null $userId
+     * @param string|null $companyId
+     * @param array|null  $metadata    Any extra info (invoice_id, etc.)
+     */
+    public static function log(
+        string  $tenantId,
+        string  $actionType,
+        string  $modelName,
+        int     $promptTokens,
+        int     $completionTokens,
+        ?string $userId = null,
+        ?string $companyId = null,
+        ?array  $metadata = null,
+    ): void {
+        $totalTokens   = $promptTokens + $completionTokens;
+        $estimatedCost = self::estimateCost($modelName, $promptTokens, $completionTokens);
+
+        try {
+            $db   = Database::getInstance();
+            $stmt = $db->prepare(
+                "INSERT INTO ai_usage_log
+                    (tenant_id, user_id, company_id, action_type, model_name,
+                     prompt_tokens, completion_tokens, total_tokens, estimated_cost,
+                     request_metadata, created_at)
+                 VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, NOW())"
+            );
+            $stmt->execute([
+                $tenantId,
+                $userId,
+                $companyId,
+                $actionType,
+                $modelName,
+                $promptTokens,
+                $completionTokens,
+                $totalTokens,
+                $estimatedCost,
+                $metadata ? json_encode($metadata, JSON_UNESCAPED_UNICODE) : null,
+            ]);
+        } catch (\Exception $e) {
+            // Logging should never break the main flow
+            error_log('[AiUsageLogger] Failed to log: ' . $e->getMessage());
+        }
+    }
+
+    /**
+     * Estimate cost in USD based on model pricing.
+     */
+    private static function estimateCost(string $model, int $inputTokens, int $outputTokens): float
+    {
+        $pricing = self::MODEL_PRICING[$model] ?? ['input' => 0.10, 'output' => 0.40];
+
+        $inputCost  = ($inputTokens / 1_000_000) * $pricing['input'];
+        $outputCost = ($outputTokens / 1_000_000) * $pricing['output'];
+
+        return round($inputCost + $outputCost, 6);
+    }
+}