// Licensed to StellaOps under the AGPL-3.0-or-later license.
// Sprint: SPRINT_20260109_009_003_BE_cve_symbol_mapping
// Task: Implement API endpoints

using System.Collections.Immutable;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.RateLimiting;
using StellaOps.Reachability.Core.CveMapping;

namespace StellaOps.ReachGraph.WebService.Controllers;

/// <summary>
/// CVE-Symbol Mapping API for querying vulnerable symbols.
/// Maps CVE identifiers to affected functions/methods for reachability analysis.
/// </summary>
[ApiController]
[Route("v1/cve-mappings")]
[Produces("application/json")]
public class CveMappingController : ControllerBase
{
    private readonly ICveSymbolMappingService _mappingService;
    private readonly ILogger<CveMappingController> _logger;

    public CveMappingController(
        ICveSymbolMappingService mappingService,
        ILogger<CveMappingController> logger)
    {
        _mappingService = mappingService;
        _logger = logger;
    }

    /// <summary>
    /// Get all symbol mappings for a CVE.
    /// </summary>
    /// <param name="cveId">The CVE identifier (e.g., CVE-2021-44228).</param>
    /// <param name="cancellationToken">Cancellation token.</param>
    /// <returns>List of vulnerable symbols for the CVE.</returns>
    [HttpGet("{cveId}")]
    [EnableRateLimiting("reachgraph-read")]
    [ProducesResponseType(typeof(CveMappingResponse), StatusCodes.Status200OK)]
    [ProducesResponseType(StatusCodes.Status404NotFound)]
    [ResponseCache(Duration = 3600, VaryByQueryKeys = new[] { "cveId" })]
    public async Task<IActionResult> GetByCveIdAsync(
        [FromRoute] string cveId,
        CancellationToken cancellationToken)
    {
        _logger.LogDebug("Fetching mappings for CVE {CveId}", cveId);

        var mappings = await _mappingService.GetMappingsForCveAsync(cveId, cancellationToken);

        if (mappings.Count == 0)
        {
            return NotFound(new ProblemDetails
            {
                Title = "CVE not found",
                Detail = $"No symbol mappings found for CVE {cveId}",
                Status = StatusCodes.Status404NotFound
            });
        }

        var response = new CveMappingResponse
        {
            CveId = cveId,
            MappingCount = mappings.Count,
            Mappings = mappings.Select(m => new CveMappingDto
            {
                Purl = m.Purl,
                Symbol = m.Symbol.Symbol,
                CanonicalId = m.Symbol.CanonicalId,
                FilePath = m.Symbol.FilePath,
                StartLine = m.Symbol.StartLine,
                EndLine = m.Symbol.EndLine,
                Source = m.Source.ToString(),
                Confidence = m.Confidence,
                VulnerabilityType = m.VulnerabilityType.ToString(),
                AffectedVersions = m.AffectedVersions.ToList(),
                FixedVersions = m.FixedVersions.ToList(),
                EvidenceUri = m.EvidenceUri
            }).ToList()
        };

        return Ok(response);
    }

    /// <summary>
    /// Get mappings for a specific package.
    /// </summary>
    /// <param name="purl">Package URL (URL-encoded).</param>
    /// <param name="cancellationToken">Cancellation token.</param>
    /// <returns>List of CVE mappings affecting the package.</returns>
    [HttpGet("by-package")]
    [EnableRateLimiting("reachgraph-read")]
    [ProducesResponseType(typeof(PackageMappingsResponse), StatusCodes.Status200OK)]
    public async Task<IActionResult> GetByPackageAsync(
        [FromQuery] string purl,
        CancellationToken cancellationToken)
    {
        if (string.IsNullOrWhiteSpace(purl))
        {
            return BadRequest(new ProblemDetails
            {
                Title = "Invalid request",
                Detail = "Package URL (purl) is required",
                Status = StatusCodes.Status400BadRequest
            });
        }

        _logger.LogDebug("Fetching mappings for package {Purl}", purl);

        var mappings = await _mappingService.GetMappingsForPackageAsync(purl, cancellationToken);

        var response = new PackageMappingsResponse
        {
            Purl = purl,
            MappingCount = mappings.Count,
            Mappings = mappings.Select(m => new CveMappingDto
            {
                CveId = m.CveId,
                Purl = m.Purl,
                Symbol = m.Symbol.Symbol,
                CanonicalId = m.Symbol.CanonicalId,
                FilePath = m.Symbol.FilePath,
                StartLine = m.Symbol.StartLine,
                EndLine = m.Symbol.EndLine,
                Source = m.Source.ToString(),
                Confidence = m.Confidence,
                VulnerabilityType = m.VulnerabilityType.ToString(),
                AffectedVersions = m.AffectedVersions.ToList(),
                FixedVersions = m.FixedVersions.ToList(),
                EvidenceUri = m.EvidenceUri
            }).ToList()
        };

        return Ok(response);
    }

    /// <summary>
    /// Search for mappings by symbol name.
    /// </summary>
    /// <param name="symbol">Symbol name or pattern.</param>
    /// <param name="language">Optional programming language filter.</param>
    /// <param name="cancellationToken">Cancellation token.</param>
    /// <returns>List of CVE mappings matching the symbol.</returns>
    [HttpGet("by-symbol")]
    [EnableRateLimiting("reachgraph-read")]
    [ProducesResponseType(typeof(SymbolMappingsResponse), StatusCodes.Status200OK)]
    public async Task<IActionResult> GetBySymbolAsync(
        [FromQuery] string symbol,
        [FromQuery] string? language,
        CancellationToken cancellationToken)
    {
        if (string.IsNullOrWhiteSpace(symbol))
        {
            return BadRequest(new ProblemDetails
            {
                Title = "Invalid request",
                Detail = "Symbol name is required",
                Status = StatusCodes.Status400BadRequest
            });
        }

        _logger.LogDebug("Searching mappings for symbol {Symbol}, language {Language}", symbol, language ?? "any");

        var mappings = await _mappingService.SearchBySymbolAsync(symbol, language, cancellationToken);

        var response = new SymbolMappingsResponse
        {
            Symbol = symbol,
            Language = language,
            MappingCount = mappings.Count,
            Mappings = mappings.Select(m => new CveMappingDto
            {
                CveId = m.CveId,
                Purl = m.Purl,
                Symbol = m.Symbol.Symbol,
                CanonicalId = m.Symbol.CanonicalId,
                FilePath = m.Symbol.FilePath,
                StartLine = m.Symbol.StartLine,
                EndLine = m.Symbol.EndLine,
                Source = m.Source.ToString(),
                Confidence = m.Confidence,
                VulnerabilityType = m.VulnerabilityType.ToString(),
                AffectedVersions = m.AffectedVersions.ToList(),
                FixedVersions = m.FixedVersions.ToList(),
                EvidenceUri = m.EvidenceUri
            }).ToList()
        };

        return Ok(response);
    }

    /// <summary>
    /// Add or update a CVE-symbol mapping.
    /// </summary>
    /// <param name="request">The mapping to add.</param>
    /// <param name="cancellationToken">Cancellation token.</param>
    /// <returns>The created or updated mapping.</returns>
    [HttpPost]
    [EnableRateLimiting("reachgraph-write")]
    [ProducesResponseType(typeof(CveMappingDto), StatusCodes.Status201Created)]
    [ProducesResponseType(typeof(CveMappingDto), StatusCodes.Status200OK)]
    [ProducesResponseType(StatusCodes.Status400BadRequest)]
    public async Task<IActionResult> UpsertMappingAsync(
        [FromBody] UpsertCveMappingRequest request,
        CancellationToken cancellationToken)
    {
        if (string.IsNullOrWhiteSpace(request.CveId))
        {
            return BadRequest(new ProblemDetails
            {
                Title = "Invalid request",
                Detail = "CVE ID is required",
                Status = StatusCodes.Status400BadRequest
            });
        }

        if (string.IsNullOrWhiteSpace(request.Purl))
        {
            return BadRequest(new ProblemDetails
            {
                Title = "Invalid request",
                Detail = "Package URL (purl) is required",
                Status = StatusCodes.Status400BadRequest
            });
        }

        if (string.IsNullOrWhiteSpace(request.Symbol))
        {
            return BadRequest(new ProblemDetails
            {
                Title = "Invalid request",
                Detail = "Symbol name is required",
                Status = StatusCodes.Status400BadRequest
            });
        }

        _logger.LogInformation("Upserting mapping: CVE {CveId}, Package {Purl}, Symbol {Symbol}",
            request.CveId, request.Purl, request.Symbol);

        if (!Enum.TryParse<MappingSource>(request.Source, ignoreCase: true, out var source))
        {
            source = MappingSource.Unknown;
        }

        if (!Enum.TryParse<VulnerabilityType>(request.VulnerabilityType, ignoreCase: true, out var vulnType))
        {
            vulnType = VulnerabilityType.Unknown;
        }

        var mapping = new CveSymbolMapping
        {
            CveId = request.CveId,
            Purl = request.Purl,
            Symbol = new VulnerableSymbol
            {
                Symbol = request.Symbol,
                CanonicalId = request.CanonicalId,
                FilePath = request.FilePath,
                StartLine = request.StartLine,
                EndLine = request.EndLine
            },
            Source = source,
            Confidence = request.Confidence ?? 0.5,
            VulnerabilityType = vulnType,
            AffectedVersions = request.AffectedVersions?.ToImmutableArray() ?? [],
            FixedVersions = request.FixedVersions?.ToImmutableArray() ?? [],
            EvidenceUri = request.EvidenceUri
        };

        var result = await _mappingService.AddOrUpdateMappingAsync(mapping, cancellationToken);

        var response = new CveMappingDto
        {
            CveId = result.CveId,
            Purl = result.Purl,
            Symbol = result.Symbol.Symbol,
            CanonicalId = result.Symbol.CanonicalId,
            FilePath = result.Symbol.FilePath,
            StartLine = result.Symbol.StartLine,
            EndLine = result.Symbol.EndLine,
            Source = result.Source.ToString(),
            Confidence = result.Confidence,
            VulnerabilityType = result.VulnerabilityType.ToString(),
            AffectedVersions = result.AffectedVersions.ToList(),
            FixedVersions = result.FixedVersions.ToList(),
            EvidenceUri = result.EvidenceUri
        };

        return CreatedAtAction(nameof(GetByCveIdAsync), new { cveId = result.CveId }, response);
    }

    /// <summary>
    /// Analyze a commit/patch to extract vulnerable symbols.
    /// </summary>
    /// <param name="request">The patch analysis request.</param>
    /// <param name="cancellationToken">Cancellation token.</param>
    /// <returns>Extracted symbols from the patch.</returns>
    [HttpPost("analyze-patch")]
    [EnableRateLimiting("reachgraph-write")]
    [ProducesResponseType(typeof(PatchAnalysisResponse), StatusCodes.Status200OK)]
    [ProducesResponseType(StatusCodes.Status400BadRequest)]
    public async Task<IActionResult> AnalyzePatchAsync(
        [FromBody] AnalyzePatchRequest request,
        CancellationToken cancellationToken)
    {
        if (string.IsNullOrWhiteSpace(request.CommitUrl) && string.IsNullOrWhiteSpace(request.DiffContent))
        {
            return BadRequest(new ProblemDetails
            {
                Title = "Invalid request",
                Detail = "Either CommitUrl or DiffContent is required",
                Status = StatusCodes.Status400BadRequest
            });
        }

        _logger.LogDebug("Analyzing patch: {CommitUrl}", request.CommitUrl ?? "(inline diff)");

        var result = await _mappingService.AnalyzePatchAsync(
            request.CommitUrl,
            request.DiffContent,
            cancellationToken);

        var response = new PatchAnalysisResponse
        {
            CommitUrl = request.CommitUrl,
            ExtractedSymbols = result.ExtractedSymbols.Select(s => new ExtractedSymbolDto
            {
                Symbol = s.Symbol,
                FilePath = s.FilePath,
                StartLine = s.StartLine,
                EndLine = s.EndLine,
                ChangeType = s.ChangeType.ToString(),
                Language = s.Language
            }).ToList(),
            AnalyzedAt = result.AnalyzedAt
        };

        return Ok(response);
    }

    /// <summary>
    /// Enrich CVE mapping from OSV database.
    /// </summary>
    /// <param name="cveId">CVE to enrich.</param>
    /// <param name="cancellationToken">Cancellation token.</param>
    /// <returns>Enriched mapping data from OSV.</returns>
    [HttpPost("{cveId}/enrich")]
    [EnableRateLimiting("reachgraph-write")]
    [ProducesResponseType(typeof(EnrichmentResponse), StatusCodes.Status200OK)]
    [ProducesResponseType(StatusCodes.Status404NotFound)]
    public async Task<IActionResult> EnrichFromOsvAsync(
        [FromRoute] string cveId,
        CancellationToken cancellationToken)
    {
        _logger.LogInformation("Enriching CVE {CveId} from OSV", cveId);

        var enrichedMappings = await _mappingService.EnrichFromOsvAsync(cveId, cancellationToken);

        if (enrichedMappings.Count == 0)
        {
            return NotFound(new ProblemDetails
            {
                Title = "CVE not found in OSV",
                Detail = $"No OSV data found for CVE {cveId}",
                Status = StatusCodes.Status404NotFound
            });
        }

        var response = new EnrichmentResponse
        {
            CveId = cveId,
            EnrichedCount = enrichedMappings.Count,
            Mappings = enrichedMappings.Select(m => new CveMappingDto
            {
                CveId = m.CveId,
                Purl = m.Purl,
                Symbol = m.Symbol.Symbol,
                CanonicalId = m.Symbol.CanonicalId,
                FilePath = m.Symbol.FilePath,
                Source = m.Source.ToString(),
                Confidence = m.Confidence,
                VulnerabilityType = m.VulnerabilityType.ToString(),
                AffectedVersions = m.AffectedVersions.ToList(),
                FixedVersions = m.FixedVersions.ToList()
            }).ToList()
        };

        return Ok(response);
    }

    /// <summary>
    /// Get mapping statistics.
    /// </summary>
    /// <param name="cancellationToken">Cancellation token.</param>
    /// <returns>Statistics about the mapping corpus.</returns>
    [HttpGet("stats")]
    [EnableRateLimiting("reachgraph-read")]
    [ProducesResponseType(typeof(MappingStatsResponse), StatusCodes.Status200OK)]
    [ResponseCache(Duration = 300)]
    public async Task<IActionResult> GetStatsAsync(CancellationToken cancellationToken)
    {
        var stats = await _mappingService.GetStatsAsync(cancellationToken);

        var response = new MappingStatsResponse
        {
            TotalMappings = stats.TotalMappings,
            UniqueCves = stats.UniqueCves,
            UniquePackages = stats.UniquePackages,
            BySource = stats.BySource,
            ByVulnerabilityType = stats.ByVulnerabilityType,
            AverageConfidence = stats.AverageConfidence,
            LastUpdated = stats.LastUpdated
        };

        return Ok(response);
    }
}

// ============================================================================
// DTOs
// ============================================================================

/// <summary>
/// Response containing CVE mappings.
/// </summary>
public record CveMappingResponse
{
    public required string CveId { get; init; }
    public int MappingCount { get; init; }
    public required List<CveMappingDto> Mappings { get; init; }
}

/// <summary>
/// Response for package-based query.
/// </summary>
public record PackageMappingsResponse
{
    public required string Purl { get; init; }
    public int MappingCount { get; init; }
    public required List<CveMappingDto> Mappings { get; init; }
}

/// <summary>
/// Response for symbol-based query.
/// </summary>
public record SymbolMappingsResponse
{
    public required string Symbol { get; init; }
    public string? Language { get; init; }
    public int MappingCount { get; init; }
    public required List<CveMappingDto> Mappings { get; init; }
}

/// <summary>
/// CVE mapping data transfer object.
/// </summary>
public record CveMappingDto
{
    public string? CveId { get; init; }
    public required string Purl { get; init; }
    public required string Symbol { get; init; }
    public string? CanonicalId { get; init; }
    public string? FilePath { get; init; }
    public int? StartLine { get; init; }
    public int? EndLine { get; init; }
    public required string Source { get; init; }
    public double Confidence { get; init; }
    public required string VulnerabilityType { get; init; }
    public List<string>? AffectedVersions { get; init; }
    public List<string>? FixedVersions { get; init; }
    public string? EvidenceUri { get; init; }
}

/// <summary>
/// Request to add/update a CVE mapping.
/// </summary>
public record UpsertCveMappingRequest
{
    public required string CveId { get; init; }
    public required string Purl { get; init; }
    public required string Symbol { get; init; }
    public string? CanonicalId { get; init; }
    public string? FilePath { get; init; }
    public int? StartLine { get; init; }
    public int? EndLine { get; init; }
    public string? Source { get; init; }
    public double? Confidence { get; init; }
    public string? VulnerabilityType { get; init; }
    public List<string>? AffectedVersions { get; init; }
    public List<string>? FixedVersions { get; init; }
    public string? EvidenceUri { get; init; }
}

/// <summary>
/// Request to analyze a patch.
/// </summary>
public record AnalyzePatchRequest
{
    public string? CommitUrl { get; init; }
    public string? DiffContent { get; init; }
}

/// <summary>
/// Response from patch analysis.
/// </summary>
public record PatchAnalysisResponse
{
    public string? CommitUrl { get; init; }
    public required List<ExtractedSymbolDto> ExtractedSymbols { get; init; }
    public DateTimeOffset AnalyzedAt { get; init; }
}

/// <summary>
/// Extracted symbol from patch.
/// </summary>
public record ExtractedSymbolDto
{
    public required string Symbol { get; init; }
    public string? FilePath { get; init; }
    public int? StartLine { get; init; }
    public int? EndLine { get; init; }
    public required string ChangeType { get; init; }
    public string? Language { get; init; }
}

/// <summary>
/// Response from OSV enrichment.
/// </summary>
public record EnrichmentResponse
{
    public required string CveId { get; init; }
    public int EnrichedCount { get; init; }
    public required List<CveMappingDto> Mappings { get; init; }
}

/// <summary>
/// Mapping statistics response.
/// </summary>
public record MappingStatsResponse
{
    public int TotalMappings { get; init; }
    public int UniqueCves { get; init; }
    public int UniquePackages { get; init; }
    public Dictionary<string, int>? BySource { get; init; }
    public Dictionary<string, int>? ByVulnerabilityType { get; init; }
    public double AverageConfidence { get; init; }
    public DateTimeOffset LastUpdated { get; init; }
}