//! Report generation system

use crate::storage::database::Database;
use crate::utils::error::gateway_error::{GatewayError, Result};
use chrono::{DateTime, Utc};
use serde::{Deserialize, Serialize};
use std::collections::HashMap;

/// Report generator for creating detailed reports
pub struct ReportGenerator {
    /// Report templates
    templates: HashMap<String, ReportTemplate>,
}

/// Report template
#[derive(Debug, Clone)]
pub struct ReportTemplate {
    /// Template name
    pub name: String,
    /// Template description
    pub description: String,
    /// Report sections
    pub sections: Vec<ReportSection>,
    /// Output format
    pub format: ReportFormat,
}

/// Report section
#[derive(Debug, Clone)]
pub struct ReportSection {
    /// Section title
    pub title: String,
    /// Section type
    pub section_type: ReportSectionType,
    /// Data queries
    pub queries: Vec<String>,
}

/// Types of report sections
#[derive(Debug, Clone)]
pub enum ReportSectionType {
    /// Summary section
    Summary,
    /// Chart section
    Chart,
    /// Table section
    Table,
    /// Metrics section
    Metrics,
    /// Recommendations section
    Recommendations,
}

/// Report output formats
#[derive(Debug, Clone)]
pub enum ReportFormat {
    /// PDF format
    Pdf,
    /// HTML format
    Html,
    /// JSON format
    Json,
    /// CSV format
    Csv,
    /// Excel format
    Excel,
}

/// Generated report
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct GeneratedReport {
    /// Report ID
    pub id: String,
    /// Report title
    pub title: String,
    /// Generation timestamp
    pub generated_at: DateTime<Utc>,
    /// Report period
    pub period_start: DateTime<Utc>,
    /// End of report period
    pub period_end: DateTime<Utc>,
    /// Report sections
    pub sections: Vec<ReportSectionData>,
    /// Summary statistics
    pub summary: ReportSummary,
}

/// Report section data
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ReportSectionData {
    /// Section title
    pub title: String,
    /// Section data
    pub data: serde_json::Value,
    /// Charts or visualizations
    pub charts: Vec<ChartData>,
}

/// Chart data for visualizations
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ChartData {
    /// Chart type
    pub chart_type: String,
    /// Chart title
    pub title: String,
    /// Data points
    pub data: Vec<DataPoint>,
    /// Chart configuration
    pub config: serde_json::Value,
}

/// Data point for charts
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct DataPoint {
    /// X-axis value
    pub x: serde_json::Value,
    /// Y-axis value
    pub y: serde_json::Value,
    /// Additional metadata
    pub metadata: Option<serde_json::Value>,
}

/// Report summary
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ReportSummary {
    /// Total requests
    pub total_requests: u64,
    /// Total cost
    pub total_cost: f64,
    /// Average response time
    pub avg_response_time: f64,
    /// Success rate
    pub success_rate: f64,
    /// Top insights
    pub key_insights: Vec<String>,
    /// Recommendations
    pub recommendations: Vec<String>,
}

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

impl ReportGenerator {
    /// Create a new report generator
    pub fn new() -> Self {
        Self {
            templates: Self::default_templates(),
        }
    }

    /// Generate a report
    pub async fn generate(
        &self,
        template_name: &str,
        _user_id: Option<&str>,
        start_date: DateTime<Utc>,
        end_date: DateTime<Utc>,
        _database: &Database,
    ) -> Result<GeneratedReport> {
        let template = self
            .templates
            .get(template_name)
            .ok_or_else(|| GatewayError::NotFound("Report template not found".to_string()))?;

        // Generate report sections
        let sections = Vec::new(); // Implement section generation

        Ok(GeneratedReport {
            id: uuid::Uuid::new_v4().to_string(),
            title: template.name.clone(),
            generated_at: Utc::now(),
            period_start: start_date,
            period_end: end_date,
            sections,
            summary: ReportSummary {
                total_requests: 0,
                total_cost: 0.0,
                avg_response_time: 0.0,
                success_rate: 0.0,
                key_insights: Vec::new(),
                recommendations: Vec::new(),
            },
        })
    }

    /// Get available templates
    pub fn templates(&self) -> &HashMap<String, ReportTemplate> {
        &self.templates
    }

    /// Default report templates
    fn default_templates() -> HashMap<String, ReportTemplate> {
        let mut templates = HashMap::new();

        templates.insert(
            "usage_summary".to_string(),
            ReportTemplate {
                name: "Usage Summary Report".to_string(),
                description: "Comprehensive usage and cost summary".to_string(),
                sections: vec![
                    ReportSection {
                        title: "Executive Summary".to_string(),
                        section_type: ReportSectionType::Summary,
                        queries: vec!["summary_stats".to_string()],
                    },
                    ReportSection {
                        title: "Cost Analysis".to_string(),
                        section_type: ReportSectionType::Chart,
                        queries: vec!["cost_trends".to_string()],
                    },
                ],
                format: ReportFormat::Pdf,
            },
        );

        templates
    }
}

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

    // ==================== ReportTemplate Tests ====================

    #[test]
    fn test_report_template_creation() {
        let template = ReportTemplate {
            name: "Test Report".to_string(),
            description: "A test report template".to_string(),
            sections: vec![],
            format: ReportFormat::Pdf,
        };

        assert_eq!(template.name, "Test Report");
        assert_eq!(template.description, "A test report template");
        assert!(template.sections.is_empty());
    }

    #[test]
    fn test_report_template_with_sections() {
        let template = ReportTemplate {
            name: "Full Report".to_string(),
            description: "Report with sections".to_string(),
            sections: vec![
                ReportSection {
                    title: "Summary".to_string(),
                    section_type: ReportSectionType::Summary,
                    queries: vec!["stats".to_string()],
                },
                ReportSection {
                    title: "Charts".to_string(),
                    section_type: ReportSectionType::Chart,
                    queries: vec!["chart_data".to_string()],
                },
            ],
            format: ReportFormat::Html,
        };

        assert_eq!(template.sections.len(), 2);
        assert_eq!(template.sections[0].title, "Summary");
        assert_eq!(template.sections[1].title, "Charts");
    }

    #[test]
    fn test_report_template_clone() {
        let template = ReportTemplate {
            name: "Clone Test".to_string(),
            description: "Testing clone".to_string(),
            sections: vec![ReportSection {
                title: "Section".to_string(),
                section_type: ReportSectionType::Table,
                queries: vec![],
            }],
            format: ReportFormat::Json,
        };

        let cloned = template.clone();
        assert_eq!(template.name, cloned.name);
        assert_eq!(template.sections.len(), cloned.sections.len());
    }

    // ==================== ReportSection Tests ====================

    #[test]
    fn test_report_section_creation() {
        let section = ReportSection {
            title: "Test Section".to_string(),
            section_type: ReportSectionType::Metrics,
            queries: vec!["query1".to_string(), "query2".to_string()],
        };

        assert_eq!(section.title, "Test Section");
        assert_eq!(section.queries.len(), 2);
    }

    #[test]
    fn test_report_section_clone() {
        let section = ReportSection {
            title: "Clone Section".to_string(),
            section_type: ReportSectionType::Recommendations,
            queries: vec!["q1".to_string()],
        };

        let cloned = section.clone();
        assert_eq!(section.title, cloned.title);
    }

    // ==================== ReportSectionType Tests ====================

    #[test]
    fn test_report_section_type_variants() {
        let summary = ReportSectionType::Summary;
        let chart = ReportSectionType::Chart;
        let table = ReportSectionType::Table;
        let metrics = ReportSectionType::Metrics;
        let recommendations = ReportSectionType::Recommendations;

        // Just verify they can be created and cloned
        let _ = summary.clone();
        let _ = chart.clone();
        let _ = table.clone();
        let _ = metrics.clone();
        let _ = recommendations.clone();
    }

    // ==================== ReportFormat Tests ====================

    #[test]
    fn test_report_format_variants() {
        let pdf = ReportFormat::Pdf;
        let html = ReportFormat::Html;
        let json = ReportFormat::Json;
        let csv = ReportFormat::Csv;
        let excel = ReportFormat::Excel;

        // Just verify they can be created and cloned
        let _ = pdf.clone();
        let _ = html.clone();
        let _ = json.clone();
        let _ = csv.clone();
        let _ = excel.clone();
    }

    // ==================== GeneratedReport Tests ====================

    #[test]
    fn test_generated_report_creation() {
        let now = Utc::now();
        let report = GeneratedReport {
            id: "report-123".to_string(),
            title: "Test Report".to_string(),
            generated_at: now,
            period_start: now - chrono::Duration::days(7),
            period_end: now,
            sections: vec![],
            summary: ReportSummary {
                total_requests: 1000,
                total_cost: 50.0,
                avg_response_time: 150.0,
                success_rate: 99.5,
                key_insights: vec!["High usage on Monday".to_string()],
                recommendations: vec!["Consider caching".to_string()],
            },
        };

        assert_eq!(report.id, "report-123");
        assert_eq!(report.summary.total_requests, 1000);
        assert_eq!(report.summary.success_rate, 99.5);
    }

    #[test]
    fn test_generated_report_with_sections() {
        let now = Utc::now();
        let report = GeneratedReport {
            id: "report-456".to_string(),
            title: "Full Report".to_string(),
            generated_at: now,
            period_start: now - chrono::Duration::days(30),
            period_end: now,
            sections: vec![
                ReportSectionData {
                    title: "Overview".to_string(),
                    data: serde_json::json!({"requests": 1000}),
                    charts: vec![],
                },
                ReportSectionData {
                    title: "Costs".to_string(),
                    data: serde_json::json!({"total": 100.0}),
                    charts: vec![ChartData {
                        chart_type: "line".to_string(),
                        title: "Cost Trend".to_string(),
                        data: vec![],
                        config: serde_json::json!({}),
                    }],
                },
            ],
            summary: ReportSummary {
                total_requests: 5000,
                total_cost: 250.0,
                avg_response_time: 100.0,
                success_rate: 98.0,
                key_insights: vec![],
                recommendations: vec![],
            },
        };

        assert_eq!(report.sections.len(), 2);
        assert_eq!(report.sections[1].charts.len(), 1);
    }

    #[test]
    fn test_generated_report_clone() {
        let now = Utc::now();
        let report = GeneratedReport {
            id: "clone-test".to_string(),
            title: "Clone Report".to_string(),
            generated_at: now,
            period_start: now,
            period_end: now,
            sections: vec![],
            summary: ReportSummary {
                total_requests: 100,
                total_cost: 10.0,
                avg_response_time: 50.0,
                success_rate: 100.0,
                key_insights: vec![],
                recommendations: vec![],
            },
        };

        let cloned = report.clone();
        assert_eq!(report.id, cloned.id);
        assert_eq!(report.summary.total_requests, cloned.summary.total_requests);
    }

    #[test]
    fn test_generated_report_serialization() {
        let now = Utc::now();
        let report = GeneratedReport {
            id: "ser-test".to_string(),
            title: "Serialization Test".to_string(),
            generated_at: now,
            period_start: now - chrono::Duration::days(1),
            period_end: now,
            sections: vec![],
            summary: ReportSummary {
                total_requests: 500,
                total_cost: 25.0,
                avg_response_time: 75.0,
                success_rate: 99.0,
                key_insights: vec!["insight1".to_string()],
                recommendations: vec!["rec1".to_string()],
            },
        };

        let json = serde_json::to_value(&report).unwrap();
        assert_eq!(json["id"], "ser-test");
        assert_eq!(json["summary"]["total_requests"], 500);
        assert_eq!(json["summary"]["key_insights"][0], "insight1");
    }

    #[test]
    fn test_generated_report_deserialization() {
        let json = r#"{
            "id": "deser-test",
            "title": "Deserialization Test",
            "generated_at": "2024-01-01T00:00:00Z",
            "period_start": "2023-12-01T00:00:00Z",
            "period_end": "2024-01-01T00:00:00Z",
            "sections": [],
            "summary": {
                "total_requests": 200,
                "total_cost": 15.5,
                "avg_response_time": 80.0,
                "success_rate": 97.5,
                "key_insights": [],
                "recommendations": []
            }
        }"#;

        let report: GeneratedReport = serde_json::from_str(json).unwrap();
        assert_eq!(report.id, "deser-test");
        assert_eq!(report.summary.total_requests, 200);
        assert_eq!(report.summary.total_cost, 15.5);
    }

    // ==================== ReportSectionData Tests ====================

    #[test]
    fn test_report_section_data_creation() {
        let section = ReportSectionData {
            title: "Test Section".to_string(),
            data: serde_json::json!({"key": "value"}),
            charts: vec![],
        };

        assert_eq!(section.title, "Test Section");
        assert!(section.charts.is_empty());
    }

    #[test]
    fn test_report_section_data_with_charts() {
        let section = ReportSectionData {
            title: "Charts Section".to_string(),
            data: serde_json::json!({}),
            charts: vec![ChartData {
                chart_type: "bar".to_string(),
                title: "Bar Chart".to_string(),
                data: vec![
                    DataPoint {
                        x: serde_json::json!("Jan"),
                        y: serde_json::json!(100),
                        metadata: None,
                    },
                    DataPoint {
                        x: serde_json::json!("Feb"),
                        y: serde_json::json!(150),
                        metadata: Some(serde_json::json!({"note": "high"})),
                    },
                ],
                config: serde_json::json!({"color": "blue"}),
            }],
        };

        assert_eq!(section.charts.len(), 1);
        assert_eq!(section.charts[0].data.len(), 2);
    }

    #[test]
    fn test_report_section_data_serialization() {
        let section = ReportSectionData {
            title: "Ser Section".to_string(),
            data: serde_json::json!({"requests": 100}),
            charts: vec![],
        };

        let json = serde_json::to_value(&section).unwrap();
        assert_eq!(json["title"], "Ser Section");
        assert_eq!(json["data"]["requests"], 100);
    }

    // ==================== ChartData Tests ====================

    #[test]
    fn test_chart_data_creation() {
        let chart = ChartData {
            chart_type: "pie".to_string(),
            title: "Distribution".to_string(),
            data: vec![],
            config: serde_json::json!({}),
        };

        assert_eq!(chart.chart_type, "pie");
        assert_eq!(chart.title, "Distribution");
    }

    #[test]
    fn test_chart_data_with_points() {
        let chart = ChartData {
            chart_type: "line".to_string(),
            title: "Trend".to_string(),
            data: vec![
                DataPoint {
                    x: serde_json::json!(0),
                    y: serde_json::json!(10),
                    metadata: None,
                },
                DataPoint {
                    x: serde_json::json!(1),
                    y: serde_json::json!(20),
                    metadata: None,
                },
                DataPoint {
                    x: serde_json::json!(2),
                    y: serde_json::json!(15),
                    metadata: None,
                },
            ],
            config: serde_json::json!({"smooth": true}),
        };

        assert_eq!(chart.data.len(), 3);
    }

    #[test]
    fn test_chart_data_clone() {
        let chart = ChartData {
            chart_type: "scatter".to_string(),
            title: "Points".to_string(),
            data: vec![DataPoint {
                x: serde_json::json!(1),
                y: serde_json::json!(2),
                metadata: None,
            }],
            config: serde_json::json!({}),
        };

        let cloned = chart.clone();
        assert_eq!(chart.chart_type, cloned.chart_type);
        assert_eq!(chart.data.len(), cloned.data.len());
    }

    #[test]
    fn test_chart_data_serialization() {
        let chart = ChartData {
            chart_type: "area".to_string(),
            title: "Area Chart".to_string(),
            data: vec![],
            config: serde_json::json!({"fill": true}),
        };

        let json = serde_json::to_value(&chart).unwrap();
        assert_eq!(json["chart_type"], "area");
        assert_eq!(json["config"]["fill"], true);
    }

    // ==================== DataPoint Tests ====================

    #[test]
    fn test_data_point_creation() {
        let point = DataPoint {
            x: serde_json::json!("2024-01-01"),
            y: serde_json::json!(100),
            metadata: None,
        };

        assert_eq!(point.x, "2024-01-01");
        assert_eq!(point.y, 100);
        assert!(point.metadata.is_none());
    }

    #[test]
    fn test_data_point_with_metadata() {
        let point = DataPoint {
            x: serde_json::json!(1),
            y: serde_json::json!(50.5),
            metadata: Some(serde_json::json!({
                "label": "Point A",
                "color": "#ff0000"
            })),
        };

        assert!(point.metadata.is_some());
        let meta = point.metadata.as_ref().unwrap();
        assert_eq!(meta["label"], "Point A");
    }

    #[test]
    fn test_data_point_clone() {
        let point = DataPoint {
            x: serde_json::json!("x"),
            y: serde_json::json!("y"),
            metadata: Some(serde_json::json!({})),
        };

        let cloned = point.clone();
        assert_eq!(point.x, cloned.x);
        assert_eq!(point.y, cloned.y);
    }

    #[test]
    fn test_data_point_serialization() {
        let point = DataPoint {
            x: serde_json::json!(10),
            y: serde_json::json!(20),
            metadata: None,
        };

        let json = serde_json::to_value(&point).unwrap();
        assert_eq!(json["x"], 10);
        assert_eq!(json["y"], 20);
    }

    // ==================== ReportSummary Tests ====================

    #[test]
    fn test_report_summary_creation() {
        let summary = ReportSummary {
            total_requests: 10000,
            total_cost: 500.0,
            avg_response_time: 120.0,
            success_rate: 99.9,
            key_insights: vec![
                "Usage increased 20%".to_string(),
                "Cost decreased 10%".to_string(),
            ],
            recommendations: vec![
                "Enable caching".to_string(),
                "Use batch requests".to_string(),
            ],
        };

        assert_eq!(summary.total_requests, 10000);
        assert_eq!(summary.total_cost, 500.0);
        assert_eq!(summary.key_insights.len(), 2);
        assert_eq!(summary.recommendations.len(), 2);
    }

    #[test]
    fn test_report_summary_empty() {
        let summary = ReportSummary {
            total_requests: 0,
            total_cost: 0.0,
            avg_response_time: 0.0,
            success_rate: 0.0,
            key_insights: vec![],
            recommendations: vec![],
        };

        assert_eq!(summary.total_requests, 0);
        assert!(summary.key_insights.is_empty());
    }

    #[test]
    fn test_report_summary_clone() {
        let summary = ReportSummary {
            total_requests: 100,
            total_cost: 10.0,
            avg_response_time: 50.0,
            success_rate: 95.0,
            key_insights: vec!["insight".to_string()],
            recommendations: vec!["rec".to_string()],
        };

        let cloned = summary.clone();
        assert_eq!(summary.total_requests, cloned.total_requests);
        assert_eq!(summary.key_insights, cloned.key_insights);
    }

    #[test]
    fn test_report_summary_serialization() {
        let summary = ReportSummary {
            total_requests: 5000,
            total_cost: 250.0,
            avg_response_time: 100.0,
            success_rate: 98.5,
            key_insights: vec!["High traffic".to_string()],
            recommendations: vec!["Scale up".to_string()],
        };

        let json = serde_json::to_value(&summary).unwrap();
        assert_eq!(json["total_requests"], 5000);
        assert_eq!(json["success_rate"], 98.5);
        assert_eq!(json["key_insights"][0], "High traffic");
    }

    // ==================== ReportGenerator Tests ====================

    #[test]
    fn test_report_generator_new() {
        let generator = ReportGenerator::new();
        assert!(!generator.templates().is_empty());
    }

    #[test]
    fn test_report_generator_default() {
        let generator = ReportGenerator::default();
        assert!(!generator.templates().is_empty());
    }

    #[test]
    fn test_report_generator_has_usage_summary_template() {
        let generator = ReportGenerator::new();
        let templates = generator.templates();

        assert!(templates.contains_key("usage_summary"));
        let template = templates.get("usage_summary").unwrap();
        assert_eq!(template.name, "Usage Summary Report");
    }

    #[test]
    fn test_report_generator_template_structure() {
        let generator = ReportGenerator::new();
        let template = generator.templates().get("usage_summary").unwrap();

        assert_eq!(template.sections.len(), 2);
        assert_eq!(template.sections[0].title, "Executive Summary");
        assert_eq!(template.sections[1].title, "Cost Analysis");
    }

    // ==================== Integration Tests ====================

    #[test]
    fn test_full_report_workflow() {
        // Create a generator
        let generator = ReportGenerator::new();

        // Verify templates exist
        assert!(generator.templates().contains_key("usage_summary"));

        // Create a sample report manually
        let now = Utc::now();
        let report = GeneratedReport {
            id: uuid::Uuid::new_v4().to_string(),
            title: "Weekly Usage Report".to_string(),
            generated_at: now,
            period_start: now - chrono::Duration::days(7),
            period_end: now,
            sections: vec![
                ReportSectionData {
                    title: "Executive Summary".to_string(),
                    data: serde_json::json!({
                        "total_requests": 50000,
                        "unique_users": 150,
                        "top_model": "gpt-4"
                    }),
                    charts: vec![],
                },
                ReportSectionData {
                    title: "Cost Analysis".to_string(),
                    data: serde_json::json!({}),
                    charts: vec![ChartData {
                        chart_type: "line".to_string(),
                        title: "Daily Cost".to_string(),
                        data: (0..7)
                            .map(|i| DataPoint {
                                x: serde_json::json!(format!("Day {}", i + 1)),
                                y: serde_json::json!(100.0 + (i as f64 * 10.0)),
                                metadata: None,
                            })
                            .collect(),
                        config: serde_json::json!({"yAxisLabel": "USD"}),
                    }],
                },
            ],
            summary: ReportSummary {
                total_requests: 50000,
                total_cost: 2500.0,
                avg_response_time: 150.0,
                success_rate: 99.2,
                key_insights: vec![
                    "GPT-4 usage increased 25%".to_string(),
                    "Response times improved by 10%".to_string(),
                ],
                recommendations: vec![
                    "Consider implementing semantic caching".to_string(),
                    "Review rate limiting strategy".to_string(),
                ],
            },
        };

        // Verify the report
        assert!(!report.id.is_empty());
        assert_eq!(report.sections.len(), 2);
        assert_eq!(report.sections[1].charts.len(), 1);
        assert_eq!(report.sections[1].charts[0].data.len(), 7);
        assert_eq!(report.summary.key_insights.len(), 2);

        // Serialize and deserialize
        let json_str = serde_json::to_string(&report).unwrap();
        let parsed: GeneratedReport = serde_json::from_str(&json_str).unwrap();
        assert_eq!(report.id, parsed.id);
        assert_eq!(report.summary.total_requests, parsed.summary.total_requests);
    }
}
