using System.Diagnostics;
using System.Text.Json;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using ProposalSystem.Application.DTOs;
using ProposalSystem.Application.Interfaces;
using ProposalSystem.Domain.Entities;
using ProposalSystem.Infrastructure.Data;

namespace ProposalSystem.Api.Controllers;

[ApiController]
[Route("api/proposals/{proposalId:guid}")]
[Authorize]
public class FilesController : ControllerBase
{
    private readonly ProposalDbContext _db;
    private readonly IS3Service _s3;
    private readonly IJobPublisher _jobPublisher;
    private readonly IAuditService _audit;
    private readonly IConfiguration _config;

    public FilesController(
        ProposalDbContext db,
        IS3Service s3,
        IJobPublisher jobPublisher,
        IAuditService audit,
        IConfiguration config)
    {
        _db = db;
        _s3 = s3;
        _jobPublisher = jobPublisher;
        _audit = audit;
        _config = config;
    }

    // Fix: API-M6 — max file size for presigned upload URLs (25 MB)
    private const long MaxFileSizeBytes = 25 * 1024 * 1024;

    [HttpPost("attachments")]
    public async Task<ActionResult<PresignedUploadResponse>> UploadAttachment(
        Guid proposalId,
        [FromQuery] string fileName,
        [FromQuery] string? vendorName,
        [FromQuery] long? fileSize,
        CancellationToken ct)
    {
        // Fix: API-M6 — reject uploads exceeding 25 MB
        if (fileSize.HasValue && fileSize.Value > MaxFileSizeBytes)
            return BadRequest(new { error = $"File size exceeds maximum allowed size of {MaxFileSizeBytes / (1024 * 1024)} MB" });

        var proposal = await _db.Proposals.FindAsync(new object[] { proposalId }, ct);
        if (proposal == null) return NotFound();

        var extension = Path.GetExtension(fileName).ToLowerInvariant();
        if (extension != ".pdf")
            return BadRequest(new { error = "Only PDF files are accepted" });

        var s3Key = $"vendors/{proposalId}/{Guid.NewGuid()}{extension}";
        var bucket = _config["UPLOADS_BUCKET"]!;

        var url = await _s3.GeneratePresignedUploadUrlAsync(bucket, s3Key, "application/pdf");

        var vendorProposal = new VendorProposal
        {
            Id = Guid.NewGuid(),
            ProposalId = proposalId,
            VendorName = vendorName ?? string.Empty,
            FileName = fileName,
            S3Key = s3Key,
            UploadedAt = DateTime.UtcNow,
            ProcessingStatus = ProcessingStatus.Pending,
        };

        _db.VendorProposals.Add(vendorProposal);
        await _db.SaveChangesAsync(ct);

        return Ok(new PresignedUploadResponse(url, s3Key, DateTime.UtcNow.AddMinutes(15), vendorProposal.Id));
    }

    [HttpPost("attachments/{vendorProposalId:guid}/confirm")]
    public async Task<ActionResult> ConfirmUpload(
        Guid proposalId,
        Guid vendorProposalId,
        CancellationToken ct)
    {
        var vendorProposal = await _db.VendorProposals
            .FirstOrDefaultAsync(v => v.Id == vendorProposalId && v.ProposalId == proposalId, ct);
        if (vendorProposal == null) return NotFound();

        if (vendorProposal.ProcessingStatus != ProcessingStatus.Pending)
            return Ok();

        await _jobPublisher.PublishAsync("pdf-extract", new
        {
            proposalId,
            s3Key = vendorProposal.S3Key,
            vendorProposalId = vendorProposal.Id,
        }, ct);

        return Ok();
    }

    [HttpGet("pdf")]
    public async Task<ActionResult<PdfDownloadResponse>> GetPdf(Guid proposalId, [FromQuery] bool regenerate = false, CancellationToken ct = default)
    {
        var devMode = _config.GetValue<bool>("Auth:DevMode");

        var pdf = regenerate ? null : await _db.GeneratedPdfs
            .Where(p => p.ProposalId == proposalId)
            .OrderByDescending(p => p.Revision)
            .FirstOrDefaultAsync(ct);

        if (pdf != null && devMode)
        {
            var localPath = Path.Combine(_getGeneratedPdfsDir(), pdf.S3Key);
            if (System.IO.File.Exists(localPath))
            {
                await _audit.LogAsync(AuditAction.Download, proposalId, $"Downloaded rev {pdf.Revision}", ct);
                return PhysicalFile(localPath, "application/pdf", Path.GetFileName(pdf.S3Key));
            }
        }

        if (pdf != null && !devMode)
        {
            var bucket = _config["GENERATED_BUCKET"]!;
            var url = await _s3.GeneratePresignedDownloadUrlAsync(bucket, pdf.S3Key, 60);
            await _audit.LogAsync(AuditAction.Download, proposalId, $"Downloaded rev {pdf.Revision}", ct);
            return Ok(new PdfDownloadResponse(url, DateTime.UtcNow.AddMinutes(60)));
        }

        if (devMode)
        {
            return await _generatePdfLocally(proposalId, ct);
        }

        await _jobPublisher.PublishAsync("pdf-generate", new { proposalId }, ct);
        return Accepted(new { message = "PDF generation queued" });
    }

    private async Task<ActionResult> _generatePdfLocally(Guid proposalId, CancellationToken ct)
    {
        var outputDir = _getGeneratedPdfsDir();
        var repoRoot = Path.GetFullPath(Path.Combine(AppContext.BaseDirectory, "..", "..", "..", "..", "..", ".."));
        var scriptPath = Path.Combine(repoRoot, "scripts", "generate-pdf-local.py");

        var psi = new ProcessStartInfo
        {
            FileName = "python3",
            Arguments = $"\"{scriptPath}\" {proposalId} \"{outputDir}\"",
            RedirectStandardOutput = true,
            RedirectStandardError = true,
            UseShellExecute = false,
        };

        using var process = Process.Start(psi)!;
        var stdout = await process.StandardOutput.ReadToEndAsync(ct);
        var stderr = await process.StandardError.ReadToEndAsync(ct);
        await process.WaitForExitAsync(ct);

        if (process.ExitCode != 0)
            return StatusCode(500, new { message = "PDF generation failed", detail = stderr });

        var result = JsonSerializer.Deserialize<JsonElement>(stdout.Trim());
        var filePath = result.GetProperty("path").GetString()!;
        var s3Key = result.GetProperty("s3Key").GetString()!;

        var proposal = await _db.Proposals.FindAsync(new object[] { proposalId }, ct);
        if (proposal == null) return NotFound();

        var generatedPdf = new GeneratedPdf
        {
            Id = Guid.NewGuid(),
            ProposalId = proposalId,
            Revision = proposal.CurrentRevision,
            S3Key = s3Key,
            GeneratedAt = DateTime.UtcNow,
            GeneratedById = Guid.Parse(User.FindFirst(System.Security.Claims.ClaimTypes.NameIdentifier)!.Value),
        };

        _db.GeneratedPdfs.Add(generatedPdf);
        await _db.SaveChangesAsync(ct);
        await _audit.LogAsync(AuditAction.GeneratePDF, proposalId, null, ct);

        return PhysicalFile(filePath, "application/pdf", Path.GetFileName(filePath));
    }

    private string _getGeneratedPdfsDir()
    {
        var repoRoot = Path.GetFullPath(Path.Combine(AppContext.BaseDirectory, "..", "..", "..", "..", "..", ".."));
        return Path.Combine(repoRoot, "generated-pdfs");
    }

    [HttpGet("pdf/versions")]
    public async Task<ActionResult<IReadOnlyList<PdfVersionResponse>>> GetPdfVersions(
        Guid proposalId,
        CancellationToken ct)
    {
        var pdfs = await _db.GeneratedPdfs
            .Where(p => p.ProposalId == proposalId)
            .OrderByDescending(p => p.Revision)
            .Select(p => new PdfVersionResponse(p.Revision, p.GeneratedAt))
            .ToListAsync(ct);

        return Ok(pdfs);
    }

    [HttpGet("pdf/{revision:int}")]
    public async Task<ActionResult<PdfDownloadResponse>> GetPdfRevision(
        Guid proposalId,
        int revision,
        CancellationToken ct)
    {
        var devMode = _config.GetValue<bool>("Auth:DevMode");

        var pdf = await _db.GeneratedPdfs
            .FirstOrDefaultAsync(p => p.ProposalId == proposalId && p.Revision == revision, ct);

        if (pdf == null) return NotFound();

        if (devMode)
        {
            var localPath = Path.Combine(_getGeneratedPdfsDir(), pdf.S3Key);
            if (System.IO.File.Exists(localPath))
            {
                await _audit.LogAsync(AuditAction.Download, proposalId, $"Downloaded rev {revision}", ct);
                return PhysicalFile(localPath, "application/pdf", Path.GetFileName(pdf.S3Key));
            }
            return NotFound();
        }

        var bucket = _config["GENERATED_BUCKET"]!;
        var url = await _s3.GeneratePresignedDownloadUrlAsync(bucket, pdf.S3Key, 60);

        await _audit.LogAsync(AuditAction.Download, proposalId, $"Downloaded rev {revision}", ct);

        return Ok(new PdfDownloadResponse(url, DateTime.UtcNow.AddMinutes(60)));
    }

    [HttpGet("vendors")]
    [Authorize(Roles = "admins,sysadmins")]
    public async Task<ActionResult<IReadOnlyList<VendorProposalResponse>>> GetVendors(
        Guid proposalId,
        CancellationToken ct)
    {
        var entities = await _db.VendorProposals
            .Where(v => v.ProposalId == proposalId)
            .OrderByDescending(v => v.UploadedAt)
            .ToListAsync(ct);

        var vendors = entities.Select(v => new VendorProposalResponse(
            v.Id,
            v.VendorName,
            v.FileName,
            v.TotalVendorCost,
            v.ProcessingStatus.ToString(),
            string.IsNullOrEmpty(v.ExtractedData) ? null : JsonSerializer.Deserialize<object>(v.ExtractedData)
        )).ToList();

        return Ok(vendors);
    }
}