//! Databento DBN File Validation Tool
//!
//! Validates integrity of downloaded Databento datasets for Wave 12 ML training.
//! Performs comprehensive checks on file integrity, bar counts, timestamps, and price/volume sanity.
//!
//! ## Usage
//! ```bash
//! cargo run -p ml --example validate_databento_files --release
//! ```

use anyhow::{Context, Result};
use dbn::decode::{DbnDecoder, DbnMetadata, DecodeRecordRef};
use dbn::OhlcvMsg;
use serde::{Deserialize, Serialize};
use std::path::{Path, PathBuf};
use std::time::Instant;

/// Expected bar counts for 180-day datasets (from download plan)
const EXPECTED_BARS_ES_180D: u64 = 1_330_000;
const EXPECTED_BARS_NQ_180D: u64 = 1_330_000;
const EXPECTED_BARS_6E_180D: u64 = 1_100_000;
const EXPECTED_BARS_ZN_180D: u64 = 900_000;

/// Acceptable tolerance for bar counts (±10%)
const BAR_COUNT_TOLERANCE: f64 = 0.10;

/// Maximum acceptable gap rate
const MAX_GAP_RATE: f64 = 0.001; // 0.1%

/// Expected time between 1-minute bars (in nanoseconds)
const ONE_MINUTE_NS: i64 = 60_000_000_000;

/// Maximum acceptable gap between bars (5 minutes in nanoseconds)
const MAX_GAP_NS: i64 = 5 * ONE_MINUTE_NS;

#[derive(Debug, Clone, Serialize, Deserialize)]
struct ValidationResult {
    symbol: String,
    file_path: String,
    file_exists: bool,
    file_size_bytes: u64,
    bar_count: u64,
    expected_bar_count: u64,
    bar_count_within_tolerance: bool,
    bar_count_deviation_pct: f64,
    timestamp_errors: u64,
    price_sanity_errors: u64,
    volume_sanity_errors: u64,
    gap_count: u64,
    gap_rate_pct: f64,
    gap_rate_acceptable: bool,
    validation_passed: bool,
    validation_time_ms: u64,
    error_message: Option<String>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
struct DataValidationReport {
    total_symbols: usize,
    passed: usize,
    failed: usize,
    total_bars: u64,
    total_validation_time_ms: u64,
    results: Vec<ValidationResult>,
}

/// Validate a single DBN file
fn validate_dbn_file(
    file_path: &Path,
    symbol: &str,
    expected_bars: u64,
) -> Result<ValidationResult> {
    let start_time = Instant::now();

    let mut result = ValidationResult {
        symbol: symbol.to_string(),
        file_path: file_path.display().to_string(),
        file_exists: file_path.exists(),
        file_size_bytes: 0,
        bar_count: 0,
        expected_bar_count: expected_bars,
        bar_count_within_tolerance: false,
        bar_count_deviation_pct: 0.0,
        timestamp_errors: 0,
        price_sanity_errors: 0,
        volume_sanity_errors: 0,
        gap_count: 0,
        gap_rate_pct: 0.0,
        gap_rate_acceptable: false,
        validation_passed: false,
        validation_time_ms: 0,
        error_message: None,
    };

    if !file_path.exists() {
        result.error_message = Some(format!("File does not exist: {}", file_path.display()));
        result.validation_time_ms = start_time.elapsed().as_millis() as u64;
        return Ok(result);
    }

    // Get file size
    let file_metadata = std::fs::metadata(file_path)?;
    result.file_size_bytes = file_metadata.len();

    // Open and decode DBN file
    let mut decoder = DbnDecoder::from_file(file_path)
        .with_context(|| format!("Failed to create DBN decoder for: {}", file_path.display()))?;

    // Read metadata
    let metadata = decoder.metadata().clone();

    println!("  Schema: {:?}", metadata.schema);
    println!("  Dataset: {}", metadata.dataset);
    println!("  Start: {}", metadata.start);
    if let Some(end) = metadata.end {
        println!("  End: {}", end);
    }

    // Validate messages
    let mut prev_timestamp: Option<i64> = None;
    let mut bar_count: u64 = 0;

    // Decode records
    while let Some(record_ref) = decoder
        .decode_record_ref()
        .with_context(|| format!("Failed to decode DBN record at bar {}", bar_count))?
    {
        if let Some(ohlcv) = record_ref.get::<OhlcvMsg>() {
            bar_count += 1;

            let ts_event = ohlcv.hd.ts_event as i64;

            // Check timestamp ordering
            if let Some(prev_ts) = prev_timestamp {
                if ts_event <= prev_ts {
                    result.timestamp_errors += 1;
                }

                // Check for gaps
                let gap = ts_event - prev_ts;
                if gap > MAX_GAP_NS {
                    result.gap_count += 1;
                }
            }
            prev_timestamp = Some(ts_event);

            // Price sanity checks (DBN uses 9 decimal places)
            let open = ohlcv.open as f64 / 1_000_000_000.0;
            let high = ohlcv.high as f64 / 1_000_000_000.0;
            let low = ohlcv.low as f64 / 1_000_000_000.0;
            let close = ohlcv.close as f64 / 1_000_000_000.0;

            if open <= 0.0 || high <= 0.0 || low <= 0.0 || close <= 0.0 {
                result.price_sanity_errors += 1;
            }

            if high < low {
                result.price_sanity_errors += 1;
            }

            if open < low || open > high || close < low || close > high {
                result.price_sanity_errors += 1;
            }

            // Volume sanity check
            if ohlcv.volume < 0 {
                result.volume_sanity_errors += 1;
            }
        }
    }

    result.bar_count = bar_count;

    // Calculate bar count deviation
    if expected_bars > 0 {
        let deviation = (bar_count as f64 - expected_bars as f64).abs() / expected_bars as f64;
        result.bar_count_deviation_pct = deviation * 100.0;
        result.bar_count_within_tolerance = deviation <= BAR_COUNT_TOLERANCE;
    } else {
        // No expected count provided, assume tolerance passed
        result.bar_count_within_tolerance = true;
    }

    // Calculate gap rate
    if bar_count > 0 {
        result.gap_rate_pct = (result.gap_count as f64 / bar_count as f64) * 100.0;
        result.gap_rate_acceptable = result.gap_rate_pct <= (MAX_GAP_RATE * 100.0);
    }

    // Overall validation pass/fail
    result.validation_passed = result.file_exists
        && result.bar_count > 0
        && result.bar_count_within_tolerance
        && result.timestamp_errors == 0
        && result.price_sanity_errors == 0
        && result.volume_sanity_errors == 0
        && result.gap_rate_acceptable;

    result.validation_time_ms = start_time.elapsed().as_millis() as u64;

    Ok(result)
}

#[tokio::main]
async fn main() -> Result<()> {
    tracing_subscriber::fmt::init();

    println!("═══════════════════════════════════════════════════════════════");
    println!("  Databento Data Validation - Wave 12 Agent W12-06");
    println!("═══════════════════════════════════════════════════════════════\n");

    let start_time = Instant::now();

    // Define expected files (180-day datasets)
    let expected_files = vec![
        ("ES.FUT", "test_data/ES_FUT_180d.dbn", EXPECTED_BARS_ES_180D),
        ("NQ.FUT", "test_data/NQ_FUT_180d.dbn", EXPECTED_BARS_NQ_180D),
        ("6E.FUT", "test_data/6E_FUT_180d.dbn", EXPECTED_BARS_6E_180D),
        ("ZN.FUT", "test_data/ZN_FUT_180d.dbn", EXPECTED_BARS_ZN_180D),
    ];

    let mut results = Vec::new();
    let mut total_bars = 0u64;

    for (symbol, file_path, expected_bars) in expected_files {
        println!("Validating {} ({})...", symbol, file_path);

        let path = PathBuf::from(file_path);
        match validate_dbn_file(&path, symbol, expected_bars) {
            Ok(result) => {
                if result.validation_passed {
                    println!(
                        "  ✅ PASS - {} bars ({} MB)",
                        result.bar_count,
                        result.file_size_bytes / 1_000_000
                    );
                } else {
                    println!(
                        "  ❌ FAIL - {}",
                        result
                            .error_message
                            .as_ref()
                            .unwrap_or(&"Validation failed".to_string())
                    );
                    if !result.file_exists {
                        println!("     File does not exist (may not be downloaded yet)");
                    }
                    if !result.bar_count_within_tolerance && result.bar_count > 0 {
                        println!(
                            "     Bar count deviation: {:.2}%",
                            result.bar_count_deviation_pct
                        );
                    }
                    if result.timestamp_errors > 0 {
                        println!("     Timestamp errors: {}", result.timestamp_errors);
                    }
                    if result.price_sanity_errors > 0 {
                        println!("     Price sanity errors: {}", result.price_sanity_errors);
                    }
                    if result.volume_sanity_errors > 0 {
                        println!("     Volume sanity errors: {}", result.volume_sanity_errors);
                    }
                    if !result.gap_rate_acceptable && result.bar_count > 0 {
                        println!(
                            "     Gap rate: {:.3}% ({} gaps)",
                            result.gap_rate_pct, result.gap_count
                        );
                    }
                }

                total_bars += result.bar_count;
                results.push(result);
            },
            Err(e) => {
                println!("  ❌ ERROR: {}", e);
                results.push(ValidationResult {
                    symbol: symbol.to_string(),
                    file_path: file_path.to_string(),
                    file_exists: false,
                    file_size_bytes: 0,
                    bar_count: 0,
                    expected_bar_count: expected_bars,
                    bar_count_within_tolerance: false,
                    bar_count_deviation_pct: 0.0,
                    timestamp_errors: 0,
                    price_sanity_errors: 0,
                    volume_sanity_errors: 0,
                    gap_count: 0,
                    gap_rate_pct: 0.0,
                    gap_rate_acceptable: false,
                    validation_passed: false,
                    validation_time_ms: 0,
                    error_message: Some(e.to_string()),
                });
            },
        }
        println!();
    }

    let total_validation_time_ms = start_time.elapsed().as_millis() as u64;

    // Generate summary report
    let passed = results.iter().filter(|r| r.validation_passed).count();
    let failed = results.len() - passed;

    let report = DataValidationReport {
        total_symbols: results.len(),
        passed,
        failed,
        total_bars,
        total_validation_time_ms,
        results,
    };

    println!("═══════════════════════════════════════════════════════════════");
    println!("  VALIDATION SUMMARY");
    println!("═══════════════════════════════════════════════════════════════");
    println!("  Total Symbols: {}", report.total_symbols);
    println!("  Passed: {} ✅", report.passed);
    println!("  Failed: {} ❌", report.failed);
    println!("  Total Bars: {}", report.total_bars);
    println!("  Validation Time: {} ms", report.total_validation_time_ms);
    println!("═══════════════════════════════════════════════════════════════\n");

    // Save validation report
    let report_json = serde_json::to_string_pretty(&report)?;
    std::fs::write("/tmp/databento_validation_report.json", &report_json)?;
    println!("✅ Validation report saved to: /tmp/databento_validation_report.json");

    // Save bar counts
    let bar_counts: serde_json::Value = serde_json::json!({
        "symbols": report.results.iter().map(|r| {
            serde_json::json!({
                "symbol": r.symbol,
                "bar_count": r.bar_count,
                "expected": r.expected_bar_count,
                "deviation_pct": r.bar_count_deviation_pct,
            })
        }).collect::<Vec<_>>(),
        "total_bars": report.total_bars,
    });
    let bar_counts_json = serde_json::to_string_pretty(&bar_counts)?;
    std::fs::write("/tmp/databento_bar_counts.json", &bar_counts_json)?;
    println!("✅ Bar counts saved to: /tmp/databento_bar_counts.json");

    // Generate markdown report
    let mut markdown = String::new();
    markdown.push_str("# Databento Data Validation Report - Wave 12 Agent W12-06\n\n");
    markdown.push_str(&format!(
        "**Date**: {}\n",
        chrono::Utc::now().format("%Y-%m-%d %H:%M:%S UTC")
    ));
    markdown.push_str(&format!(
        "**Validation Time**: {} ms\n\n",
        report.total_validation_time_ms
    ));
    markdown.push_str("---\n\n");
    markdown.push_str("## Executive Summary\n\n");
    markdown.push_str(&format!("- **Total Symbols**: {}\n", report.total_symbols));
    markdown.push_str(&format!("- **Passed**: {} ✅\n", report.passed));
    markdown.push_str(&format!("- **Failed**: {} ❌\n", report.failed));
    markdown.push_str(&format!("- **Total Bars**: {}\n", report.total_bars));
    markdown.push_str(&format!(
        "- **Overall Status**: {}\n\n",
        if report.failed == 0 {
            "✅ ALL PASSED"
        } else {
            "❌ VALIDATION FAILURES"
        }
    ));
    markdown.push_str("---\n\n");
    markdown.push_str("## Validation Results by Symbol\n\n");

    for result in &report.results {
        markdown.push_str(&format!(
            "### {} - {}\n\n",
            result.symbol,
            if result.validation_passed {
                "✅ PASS"
            } else {
                "❌ FAIL"
            }
        ));
        markdown.push_str(&format!("- **File**: `{}`\n", result.file_path));
        markdown.push_str(&format!(
            "- **File Exists**: {}\n",
            if result.file_exists {
                "✅ Yes"
            } else {
                "❌ No"
            }
        ));
        markdown.push_str(&format!(
            "- **File Size**: {} MB\n",
            result.file_size_bytes / 1_000_000
        ));
        markdown.push_str(&format!(
            "- **Bar Count**: {} (expected: {})\n",
            result.bar_count, result.expected_bar_count
        ));
        markdown.push_str(&format!(
            "- **Bar Count Deviation**: {:.2}%\n",
            result.bar_count_deviation_pct
        ));
        markdown.push_str(&format!(
            "- **Bar Count Within Tolerance**: {}\n",
            if result.bar_count_within_tolerance {
                "✅ Yes"
            } else {
                "❌ No"
            }
        ));
        markdown.push_str(&format!(
            "- **Timestamp Errors**: {}\n",
            result.timestamp_errors
        ));
        markdown.push_str(&format!(
            "- **Price Sanity Errors**: {}\n",
            result.price_sanity_errors
        ));
        markdown.push_str(&format!(
            "- **Volume Sanity Errors**: {}\n",
            result.volume_sanity_errors
        ));
        markdown.push_str(&format!("- **Gap Count**: {}\n", result.gap_count));
        markdown.push_str(&format!("- **Gap Rate**: {:.3}%\n", result.gap_rate_pct));
        markdown.push_str(&format!(
            "- **Gap Rate Acceptable**: {}\n",
            if result.gap_rate_acceptable {
                "✅ Yes"
            } else {
                "❌ No"
            }
        ));
        markdown.push_str(&format!(
            "- **Validation Time**: {} ms\n",
            result.validation_time_ms
        ));
        if let Some(error) = &result.error_message {
            markdown.push_str(&format!("- **Error**: {}\n", error));
        }
        markdown.push_str("\n");
    }

    markdown.push_str("---\n\n");
    markdown.push_str("## Next Steps\n\n");
    if report.failed > 0 {
        markdown.push_str("❌ **Action Required**: Some validations failed. Please:\n\n");
        for result in &report.results {
            if !result.validation_passed {
                if !result.file_exists {
                    markdown.push_str(&format!(
                        "- Download {} from Databento (Agent W12-02 to W12-05)\n",
                        result.symbol
                    ));
                } else {
                    markdown.push_str(&format!(
                        "- Investigate {} validation errors\n",
                        result.symbol
                    ));
                }
            }
        }
    } else {
        markdown.push_str("✅ **All validations passed!** Ready to proceed with:\n\n");
        markdown.push_str("- Wave 13: ML model retraining with 180-day datasets\n");
        markdown.push_str("- Wave 14: Wave Comparison Backtest (Wave C vs Wave D)\n");
        markdown.push_str("- Wave 15: Production deployment\n");
    }

    std::fs::write("/tmp/databento_validation_report.md", &markdown)?;
    println!("✅ Markdown report saved to: /tmp/databento_validation_report.md\n");

    // Exit with appropriate status code
    if report.failed > 0 {
        eprintln!("❌ Validation failed for {} symbols", report.failed);
        std::process::exit(1);
    } else {
        println!("✅ All validations passed!");
        Ok(())
    }
}