feat: integrate Firebase Analytics, add Google Maps dependencies, and expose new GA4 metric API endpoints.

backend/Program.cs

@@ -169,10 +169,180 @@ app.MapGet("/api/metrics/general", async (
         Console.WriteLine($"Error: {ex}");
         return Results.Problem($"Analytics API Error: {ex.Message}");
     }
+
 })
 .WithName("GetGeneralMetrics")
 .WithOpenApi();
 
+    // 3. Tech Overview (OS & App Version)
+    // GET /api/metrics/tech?from=x&to=y
+    app.MapGet("/api/metrics/tech", async (
+        [FromServices] AnalyticsDataService service,
+        [FromQuery] string? from, 
+        [FromQuery] string? to) =>
+    {
+        var startDate = from ?? "30daysAgo";
+        var endDate = to ?? "today";
+
+        // Request for OS
+        var requestOS = new RunReportRequest
+        {
+            Property = $"properties/{ga4PropertyId}",
+            DateRanges = new List<DateRange> { new DateRange { StartDate = startDate, EndDate = endDate } },
+            Dimensions = new List<Dimension> { new Dimension { Name = "operatingSystem" } },
+            Metrics = new List<Metric> { new Metric { Name = "activeUsers" } }
+        };
+
+        // Request for App Version
+        var requestVersion = new RunReportRequest
+        {
+            Property = $"properties/{ga4PropertyId}",
+            DateRanges = new List<DateRange> { new DateRange { StartDate = startDate, EndDate = endDate } },
+            Dimensions = new List<Dimension> { new Dimension { Name = "appVersion" } },
+            Metrics = new List<Metric> { new Metric { Name = "activeUsers" } } // use active users to see version adoption
+        };
+
+        try
+        {
+            var responseOS = await service.Properties.RunReport(requestOS, $"properties/{ga4PropertyId}").ExecuteAsync();
+            var responseVersion = await service.Properties.RunReport(requestVersion, $"properties/{ga4PropertyId}").ExecuteAsync();
+
+            var osData = responseOS.Rows?.Select(row => new { 
+                os = row.DimensionValues[0].Value, 
+                users = int.Parse(row.MetricValues[0].Value) 
+            }) ?? Enumerable.Empty<object>();
+
+            var versionData = responseVersion.Rows?.Select(row => new { 
+                version = row.DimensionValues[0].Value, 
+                users = int.Parse(row.MetricValues[0].Value) 
+            }) ?? Enumerable.Empty<object>();
+
+            return Results.Ok(new { operatingSystems = osData, appVersions = versionData });
+        }
+        catch (Exception ex)
+        {
+             return Results.Problem($"Analytics API Error: {ex.Message}");
+        }
+    })
+    .WithName("GetTechOverview")
+    .WithOpenApi();
+
+    // 4. Top Events
+    // GET /api/metrics/events?from=x&to=y
+    app.MapGet("/api/metrics/events", async (
+        [FromServices] AnalyticsDataService service,
+        [FromQuery] string? from, 
+        [FromQuery] string? to) =>
+    {
+        var startDate = from ?? "30daysAgo";
+        var endDate = to ?? "today";
+
+        var request = new RunReportRequest
+        {
+            Property = $"properties/{ga4PropertyId}",
+            DateRanges = new List<DateRange> { new DateRange { StartDate = startDate, EndDate = endDate } },
+            Dimensions = new List<Dimension> { new Dimension { Name = "eventName" } },
+            Metrics = new List<Metric> { new Metric { Name = "eventCount" }, new Metric { Name = "activeUsers" } },
+            OrderBys = new List<OrderBy> { new OrderBy { Desc = true, Metric = new MetricOrderBy { MetricName = "eventCount" } } },
+            Limit = 20
+        };
+
+        try
+        {
+            var response = await service.Properties.RunReport(request, $"properties/{ga4PropertyId}").ExecuteAsync();
+            var result = response.Rows?.Select(row => new { 
+                eventName = row.DimensionValues[0].Value, 
+                count = int.Parse(row.MetricValues[0].Value),
+                users = int.Parse(row.MetricValues[1].Value)
+            }) ?? Enumerable.Empty<object>();
+
+            return Results.Ok(result);
+        }
+         catch (Exception ex)
+        {
+             return Results.Problem($"Analytics API Error: {ex.Message}");
+        }
+    })
+    .WithName("GetTopEvents")
+    .WithOpenApi();
+
+    // 5. Top Screens
+    // GET /api/metrics/screens?from=x&to=y
+    app.MapGet("/api/metrics/screens", async (
+        [FromServices] AnalyticsDataService service,
+        [FromQuery] string? from, 
+        [FromQuery] string? to) =>
+    {
+        var startDate = from ?? "30daysAgo";
+        var endDate = to ?? "today";
+
+        var request = new RunReportRequest
+        {
+            Property = $"properties/{ga4PropertyId}",
+            DateRanges = new List<DateRange> { new DateRange { StartDate = startDate, EndDate = endDate } },
+            // GA4 uses 'unifiedScreenName' or 'pagePath' depending on setup, usually 'unifiedScreenName' for apps
+            Dimensions = new List<Dimension> { new Dimension { Name = "unifiedScreenName" } }, 
+            Metrics = new List<Metric> { new Metric { Name = "screenPageViews" }, new Metric { Name = "activeUsers" } },
+            OrderBys = new List<OrderBy> { new OrderBy { Desc = true, Metric = new MetricOrderBy { MetricName = "screenPageViews" } } },
+            Limit = 20
+        };
+
+        try
+        {
+            var response = await service.Properties.RunReport(request, $"properties/{ga4PropertyId}").ExecuteAsync();
+            var result = response.Rows?.Select(row => new { 
+                screenName = row.DimensionValues[0].Value, 
+                views = int.Parse(row.MetricValues[0].Value),
+                users = int.Parse(row.MetricValues[1].Value)
+            }) ?? Enumerable.Empty<object>();
+
+            return Results.Ok(result);
+        }
+         catch (Exception ex)
+        {
+             return Results.Problem($"Analytics API Error: {ex.Message}");
+        }
+    })
+    .WithName("GetTopScreens")
+    .WithOpenApi();
+
+    // 6. User Retention (New vs Returning)
+    // GET /api/metrics/retention?from=x&to=y
+    app.MapGet("/api/metrics/retention", async (
+        [FromServices] AnalyticsDataService service,
+        [FromQuery] string? from, 
+        [FromQuery] string? to) =>
+    {
+        var startDate = from ?? "30daysAgo";
+        var endDate = to ?? "today";
+
+        var request = new RunReportRequest
+        {
+            Property = $"properties/{ga4PropertyId}",
+            DateRanges = new List<DateRange> { new DateRange { StartDate = startDate, EndDate = endDate } },
+            Dimensions = new List<Dimension> { new Dimension { Name = "newVsReturning" } }, 
+            Metrics = new List<Metric> { new Metric { Name = "activeUsers" }, new Metric { Name = "sessions" } }
+        };
+
+        try
+        {
+            var response = await service.Properties.RunReport(request, $"properties/{ga4PropertyId}").ExecuteAsync();
+            var result = response.Rows?.Select(row => new { 
+                type = row.DimensionValues[0].Value, 
+                users = int.Parse(row.MetricValues[0].Value),
+                sessions = int.Parse(row.MetricValues[1].Value)
+            }) ?? Enumerable.Empty<object>();
+
+            return Results.Ok(result);
+        }
+        catch (Exception ex)
+        {
+             return Results.Problem($"Analytics API Error: {ex.Message}");
+        }
+    })
+    .WithName("GetUserRetention")
+    .WithOpenApi();
+
 app.Run();
 
 // Helper to format GA4 YYYYMMDD to YYYY-MM-DD