cstats-core 0.1.1

//! Local usage tracking for Anthropic API calls

use chrono::{DateTime, Utc};
use serde::{Deserialize, Serialize};
use std::collections::HashMap;
use std::sync::Arc;
use tokio::sync::RwLock;

use crate::Result;

use super::{
    AnthropicUsageStats, ApiCallStats, CostBreakdown, RateLimitInfo, TokenUsage, UsagePeriod,
};

/// Local usage tracker for Anthropic API calls
#[derive(Debug, Clone)]
pub struct LocalUsageTracker {
    data: Arc<RwLock<UsageData>>,
}

/// Internal usage data storage
#[derive(Debug, Clone, Serialize, Deserialize)]
struct UsageData {
    calls: Vec<ApiCallRecord>,
    session_start: DateTime<Utc>,
}

/// Record of an individual API call
#[derive(Debug, Clone, Serialize, Deserialize)]
struct ApiCallRecord {
    timestamp: DateTime<Utc>,
    model: String,
    input_tokens: u32,
    output_tokens: u32,
    response_time_ms: u64,
    success: bool,
    cost_usd: f64,
    request_id: Option<String>,
}

impl LocalUsageTracker {
    /// Create a new usage tracker
    pub fn new() -> Self {
        Self {
            data: Arc::new(RwLock::new(UsageData {
                calls: Vec::new(),
                session_start: Utc::now(),
            })),
        }
    }

    /// Record an API call
    pub async fn record_call(
        &self,
        model: &str,
        input_tokens: u32,
        output_tokens: u32,
        response_time_ms: u64,
        success: bool,
        request_id: Option<String>,
    ) -> Result<()> {
        let cost_usd = self.estimate_cost(model, input_tokens, output_tokens);

        let record = ApiCallRecord {
            timestamp: Utc::now(),
            model: model.to_string(),
            input_tokens,
            output_tokens,
            response_time_ms,
            success,
            cost_usd,
            request_id,
        };

        let mut data = self.data.write().await;
        data.calls.push(record);

        Ok(())
    }

    /// Get usage statistics for a time period
    pub async fn get_usage_stats(
        &self,
        start_time: DateTime<Utc>,
        end_time: DateTime<Utc>,
    ) -> Result<AnthropicUsageStats> {
        let data = self.data.read().await;

        let calls: Vec<&ApiCallRecord> = data
            .calls
            .iter()
            .filter(|call| call.timestamp >= start_time && call.timestamp <= end_time)
            .collect();

        Ok(self.create_stats_from_calls(&calls, start_time, end_time))
    }

    /// Get estimated rate limit information
    pub async fn get_rate_limit_info(&self) -> Result<RateLimitInfo> {
        Ok(RateLimitInfo {
            requests_per_minute: 1000,
            requests_remaining: 1000,
            reset_time: Utc::now() + chrono::Duration::seconds(60),
            tokens_per_minute: Some(50_000),
            tokens_remaining: Some(50_000),
        })
    }

    /// Clear all recorded data
    pub async fn clear(&self) -> Result<()> {
        let mut data = self.data.write().await;
        data.calls.clear();
        data.session_start = Utc::now();
        Ok(())
    }

    /// Get the number of recorded calls
    pub async fn call_count(&self) -> usize {
        let data = self.data.read().await;
        data.calls.len()
    }

    /// Estimate cost for tokens based on model pricing
    fn estimate_cost(&self, model: &str, input_tokens: u32, output_tokens: u32) -> f64 {
        // Simplified cost estimation
        let (input_rate, output_rate) = match model {
            "claude-3-haiku-20240307" => (0.25, 1.25),
            "claude-3-sonnet-20240229" => (3.0, 15.0),
            "claude-3-opus-20240229" => (15.0, 75.0),
            "claude-3-5-sonnet-20241022" => (3.0, 15.0),
            "claude-3-5-sonnet-20240620" => (3.0, 15.0),
            "claude-3-5-haiku-20241022" => (1.0, 5.0),
            _ => (3.0, 15.0), // Default to Sonnet pricing
        };

        let input_cost = (input_tokens as f64 / 1_000_000.0) * input_rate;
        let output_cost = (output_tokens as f64 / 1_000_000.0) * output_rate;

        input_cost + output_cost
    }

    /// Create usage statistics from call records
    fn create_stats_from_calls(
        &self,
        calls: &[&ApiCallRecord],
        start_time: DateTime<Utc>,
        end_time: DateTime<Utc>,
    ) -> AnthropicUsageStats {
        if calls.is_empty() {
            return self.create_empty_stats(start_time, end_time);
        }

        let token_usage = self.calculate_token_usage(calls);
        let api_calls = self.calculate_api_stats(calls);
        let costs = self.calculate_costs(calls);

        AnthropicUsageStats {
            token_usage,
            api_calls,
            costs,
            model_usage: vec![], // Simplified for now
            period: UsagePeriod {
                start: start_time,
                end: end_time,
                period_type: "local_tracking".to_string(),
            },
        }
    }

    /// Calculate token usage statistics
    fn calculate_token_usage(&self, calls: &[&ApiCallRecord]) -> TokenUsage {
        let total_input: u64 = calls.iter().map(|c| c.input_tokens as u64).sum();
        let total_output: u64 = calls.iter().map(|c| c.output_tokens as u64).sum();

        TokenUsage {
            input_tokens: total_input,
            output_tokens: total_output,
            total_tokens: total_input + total_output,
            by_model: HashMap::new(), // Simplified for now
        }
    }

    /// Calculate API call statistics
    fn calculate_api_stats(&self, calls: &[&ApiCallRecord]) -> ApiCallStats {
        let total_calls = calls.len() as u64;
        let successful_calls = calls.iter().filter(|c| c.success).count() as u64;
        let failed_calls = total_calls - successful_calls;

        let avg_response_time_ms = if !calls.is_empty() {
            calls.iter().map(|c| c.response_time_ms).sum::<u64>() as f64 / calls.len() as f64
        } else {
            0.0
        };

        ApiCallStats {
            total_calls,
            successful_calls,
            failed_calls,
            avg_response_time_ms,
            by_model: HashMap::new(), // Simplified for now
            hourly_breakdown: vec![], // Simplified for now
        }
    }

    /// Calculate cost breakdown
    fn calculate_costs(&self, calls: &[&ApiCallRecord]) -> CostBreakdown {
        let total_cost_usd: f64 = calls.iter().map(|c| c.cost_usd).sum();

        CostBreakdown {
            total_cost_usd,
            by_model: HashMap::new(), // Simplified for now
            by_token_type: super::TokenCostBreakdown {
                input_cost_usd: total_cost_usd * 0.2,  // Rough estimate
                output_cost_usd: total_cost_usd * 0.8, // Rough estimate
            },
            estimated_monthly_cost_usd: total_cost_usd * 30.0,
        }
    }

    /// Create empty stats structure
    fn create_empty_stats(
        &self,
        start_time: DateTime<Utc>,
        end_time: DateTime<Utc>,
    ) -> AnthropicUsageStats {
        AnthropicUsageStats {
            token_usage: TokenUsage {
                input_tokens: 0,
                output_tokens: 0,
                total_tokens: 0,
                by_model: HashMap::new(),
            },
            api_calls: ApiCallStats {
                total_calls: 0,
                successful_calls: 0,
                failed_calls: 0,
                avg_response_time_ms: 0.0,
                by_model: HashMap::new(),
                hourly_breakdown: vec![],
            },
            costs: CostBreakdown {
                total_cost_usd: 0.0,
                by_model: HashMap::new(),
                by_token_type: super::TokenCostBreakdown {
                    input_cost_usd: 0.0,
                    output_cost_usd: 0.0,
                },
                estimated_monthly_cost_usd: 0.0,
            },
            model_usage: vec![],
            period: UsagePeriod {
                start: start_time,
                end: end_time,
                period_type: "empty".to_string(),
            },
        }
    }
}

impl Default for LocalUsageTracker {
    fn default() -> Self {
        Self::new()
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[tokio::test]
    async fn test_usage_tracker_new() {
        let tracker = LocalUsageTracker::new();
        let count = tracker.call_count().await;
        assert_eq!(count, 0);
    }

    #[tokio::test]
    async fn test_usage_tracker_basic() {
        let tracker = LocalUsageTracker::new();

        tracker
            .record_call("claude-3-haiku-20240307", 100, 50, 500, true, None)
            .await
            .unwrap();

        let count = tracker.call_count().await;
        assert_eq!(count, 1);

        let end_time = Utc::now();
        let start_time = end_time - chrono::Duration::hours(1);

        let stats = tracker.get_usage_stats(start_time, end_time).await.unwrap();
        assert_eq!(stats.token_usage.total_tokens, 150);
        assert_eq!(stats.api_calls.total_calls, 1);
        assert_eq!(stats.api_calls.successful_calls, 1);
        assert_eq!(stats.api_calls.failed_calls, 0);
    }

    #[tokio::test]
    async fn test_record_multiple_calls() {
        let tracker = LocalUsageTracker::new();

        // Record successful call
        tracker
            .record_call(
                "claude-3-haiku-20240307",
                100,
                50,
                500,
                true,
                Some("req-1".to_string()),
            )
            .await
            .unwrap();

        // Record failed call
        tracker
            .record_call(
                "claude-3-sonnet-20240229",
                200,
                0,
                1000,
                false,
                Some("req-2".to_string()),
            )
            .await
            .unwrap();

        // Record another successful call
        tracker
            .record_call("claude-3-opus-20240229", 300, 100, 750, true, None)
            .await
            .unwrap();

        let count = tracker.call_count().await;
        assert_eq!(count, 3);

        let end_time = Utc::now();
        let start_time = end_time - chrono::Duration::hours(1);

        let stats = tracker.get_usage_stats(start_time, end_time).await.unwrap();
        assert_eq!(stats.token_usage.input_tokens, 600); // 100 + 200 + 300
        assert_eq!(stats.token_usage.output_tokens, 150); // 50 + 0 + 100
        assert_eq!(stats.token_usage.total_tokens, 750);
        assert_eq!(stats.api_calls.total_calls, 3);
        assert_eq!(stats.api_calls.successful_calls, 2);
        assert_eq!(stats.api_calls.failed_calls, 1);
        assert_eq!(stats.api_calls.avg_response_time_ms, 750.0); // (500 + 1000 + 750) / 3
    }

    #[tokio::test]
    async fn test_cost_estimation() {
        let tracker = LocalUsageTracker::new();

        // Test different models
        let haiku_cost = tracker.estimate_cost("claude-3-haiku-20240307", 1_000_000, 1_000_000);
        let sonnet_cost = tracker.estimate_cost("claude-3-sonnet-20240229", 1_000_000, 1_000_000);
        let opus_cost = tracker.estimate_cost("claude-3-opus-20240229", 1_000_000, 1_000_000);

        assert!(haiku_cost > 0.0);
        assert!(sonnet_cost > haiku_cost);
        assert!(opus_cost > sonnet_cost);

        // Test specific values
        assert_eq!(haiku_cost, 1.5); // (0.25 + 1.25) for 1M tokens each
        assert_eq!(sonnet_cost, 18.0); // (3.0 + 15.0) for 1M tokens each
        assert_eq!(opus_cost, 90.0); // (15.0 + 75.0) for 1M tokens each

        // Test unknown model defaults to Sonnet pricing
        let unknown_cost = tracker.estimate_cost("claude-unknown-model", 1_000_000, 1_000_000);
        assert_eq!(unknown_cost, sonnet_cost);
    }

    #[tokio::test]
    async fn test_clear_data() {
        let tracker = LocalUsageTracker::new();

        // Add some data
        tracker
            .record_call("claude-3-haiku-20240307", 100, 50, 500, true, None)
            .await
            .unwrap();

        assert_eq!(tracker.call_count().await, 1);

        // Clear data
        tracker.clear().await.unwrap();
        assert_eq!(tracker.call_count().await, 0);

        // Verify stats are empty
        let end_time = Utc::now();
        let start_time = end_time - chrono::Duration::hours(1);
        let stats = tracker.get_usage_stats(start_time, end_time).await.unwrap();
        assert_eq!(stats.token_usage.total_tokens, 0);
        assert_eq!(stats.api_calls.total_calls, 0);
        assert_eq!(stats.costs.total_cost_usd, 0.0);
    }

    #[tokio::test]
    async fn test_get_usage_stats_empty() {
        let tracker = LocalUsageTracker::new();

        let end_time = Utc::now();
        let start_time = end_time - chrono::Duration::hours(1);

        let stats = tracker.get_usage_stats(start_time, end_time).await.unwrap();
        assert_eq!(stats.token_usage.total_tokens, 0);
        assert_eq!(stats.api_calls.total_calls, 0);
        assert_eq!(stats.costs.total_cost_usd, 0.0);
        assert_eq!(stats.period.period_type, "empty");
    }

    #[tokio::test]
    async fn test_get_usage_stats_time_filtering() {
        let tracker = LocalUsageTracker::new();

        // Record a call
        tracker
            .record_call("claude-3-haiku-20240307", 100, 50, 500, true, None)
            .await
            .unwrap();

        // Query for future time range (should be empty)
        let future_start = Utc::now() + chrono::Duration::hours(1);
        let future_end = future_start + chrono::Duration::hours(1);
        let future_stats = tracker
            .get_usage_stats(future_start, future_end)
            .await
            .unwrap();
        assert_eq!(future_stats.token_usage.total_tokens, 0);
        assert_eq!(future_stats.api_calls.total_calls, 0);

        // Query for past time range (should include the call)
        let past_end = Utc::now() + chrono::Duration::minutes(1); // slight buffer for timing
        let past_start = past_end - chrono::Duration::hours(1);
        let past_stats = tracker.get_usage_stats(past_start, past_end).await.unwrap();
        assert_eq!(past_stats.token_usage.total_tokens, 150);
        assert_eq!(past_stats.api_calls.total_calls, 1);
    }

    #[tokio::test]
    async fn test_get_rate_limit_info() {
        let tracker = LocalUsageTracker::new();
        let rate_limit = tracker.get_rate_limit_info().await.unwrap();

        assert_eq!(rate_limit.requests_per_minute, 1000);
        assert_eq!(rate_limit.requests_remaining, 1000);
        assert_eq!(rate_limit.tokens_per_minute, Some(50_000));
        assert_eq!(rate_limit.tokens_remaining, Some(50_000));
        assert!(rate_limit.reset_time > Utc::now());
    }

    #[tokio::test]
    async fn test_cost_calculation_precision() {
        let tracker = LocalUsageTracker::new();

        // Test small token amounts
        tracker
            .record_call("claude-3-haiku-20240307", 1000, 500, 500, true, None)
            .await
            .unwrap();

        let end_time = Utc::now();
        let start_time = end_time - chrono::Duration::hours(1);
        let stats = tracker.get_usage_stats(start_time, end_time).await.unwrap();

        // Expected cost: (1000/1M * 0.25) + (500/1M * 1.25) = 0.00025 + 0.000625 = 0.000875
        let expected_cost = 0.000875;
        assert!((stats.costs.total_cost_usd - expected_cost).abs() < f64::EPSILON);

        // Check cost breakdown approximation (simplified in current implementation)
        assert!(stats.costs.by_token_type.input_cost_usd > 0.0);
        assert!(stats.costs.by_token_type.output_cost_usd > 0.0);
        let total_cost_breakdown =
            stats.costs.by_token_type.input_cost_usd + stats.costs.by_token_type.output_cost_usd;
        assert!((total_cost_breakdown - stats.costs.total_cost_usd).abs() < f64::EPSILON);
    }

    #[tokio::test]
    async fn test_token_usage_calculation() {
        let tracker = LocalUsageTracker::new();

        tracker
            .record_call("claude-3-haiku-20240307", 100, 50, 500, true, None)
            .await
            .unwrap();

        tracker
            .record_call("claude-3-sonnet-20240229", 200, 75, 600, true, None)
            .await
            .unwrap();

        let end_time = Utc::now();
        let start_time = end_time - chrono::Duration::hours(1);
        let stats = tracker.get_usage_stats(start_time, end_time).await.unwrap();

        assert_eq!(stats.token_usage.input_tokens, 300);
        assert_eq!(stats.token_usage.output_tokens, 125);
        assert_eq!(stats.token_usage.total_tokens, 425);

        // Verify model breakdown is empty in simplified implementation
        assert!(stats.token_usage.by_model.is_empty());
    }

    #[tokio::test]
    async fn test_api_call_stats_calculation() {
        let tracker = LocalUsageTracker::new();

        // Mix of successful and failed calls with different response times
        tracker
            .record_call("claude-3-haiku-20240307", 100, 50, 200, true, None)
            .await
            .unwrap();

        tracker
            .record_call("claude-3-haiku-20240307", 100, 0, 300, false, None)
            .await
            .unwrap();

        tracker
            .record_call("claude-3-sonnet-20240229", 200, 75, 500, true, None)
            .await
            .unwrap();

        let end_time = Utc::now();
        let start_time = end_time - chrono::Duration::hours(1);
        let stats = tracker.get_usage_stats(start_time, end_time).await.unwrap();

        assert_eq!(stats.api_calls.total_calls, 3);
        assert_eq!(stats.api_calls.successful_calls, 2);
        assert_eq!(stats.api_calls.failed_calls, 1);

        // Average response time: (200 + 300 + 500) / 3 = 333.33...
        let expected_avg = 1000.0 / 3.0;
        assert!((stats.api_calls.avg_response_time_ms - expected_avg).abs() < 0.01);
    }

    #[tokio::test]
    async fn test_monthly_cost_estimation() {
        let tracker = LocalUsageTracker::new();

        tracker
            .record_call("claude-3-haiku-20240307", 100, 50, 500, true, None)
            .await
            .unwrap();

        let end_time = Utc::now();
        let start_time = end_time - chrono::Duration::hours(1);
        let stats = tracker.get_usage_stats(start_time, end_time).await.unwrap();

        // Monthly cost should be daily cost * 30
        let expected_monthly = stats.costs.total_cost_usd * 30.0;
        assert_eq!(stats.costs.estimated_monthly_cost_usd, expected_monthly);
    }

    #[tokio::test]
    async fn test_default_trait() {
        let tracker1 = LocalUsageTracker::new();
        let tracker2 = LocalUsageTracker::default();

        // Both should start with zero calls
        assert_eq!(tracker1.call_count().await, 0);
        assert_eq!(tracker2.call_count().await, 0);
    }

    #[tokio::test]
    async fn test_concurrent_access() {
        let tracker = LocalUsageTracker::new();

        // Clone tracker for concurrent access
        let tracker_clone = tracker.clone();

        // Spawn concurrent tasks
        let handle1 = tokio::spawn(async move {
            tracker_clone
                .record_call("claude-3-haiku-20240307", 100, 50, 500, true, None)
                .await
        });

        let handle2 = tokio::spawn(async move {
            tracker
                .record_call("claude-3-sonnet-20240229", 200, 75, 600, true, None)
                .await
        });

        // Wait for both tasks
        let (result1, result2) = tokio::join!(handle1, handle2);
        assert!(result1.unwrap().is_ok());
        assert!(result2.unwrap().is_ok());
    }
}