using Gateway.Data;
using Gateway.Security;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Data.SqlClient;
using System.Data;
using System.Text.Json;

namespace Gateway.Controllers;

/// <summary>
/// Client-facing document endpoints.
/// All operations are scoped to the authenticated client — clientId is always
/// injected from ClientContext, never trusted from the request body.
///
/// POST /api/documents/list         - List client's own documents
/// POST /api/documents              - Upload a document (multipart)
/// GET  /api/documents/{id}/download - Download (enforces client ownership)
/// DELETE /api/documents/{id}       - Soft delete (enforces client ownership)
/// </summary>
[ApiController]
[Route("api/documents")]
public sealed class ClientDocumentController : ControllerBase
{
    private readonly SqlService _sql;
    private readonly ClientContext _client;
    private readonly IConfiguration _config;
    private readonly AuthorizationGuard _guard;
    private readonly ILogger<ClientDocumentController> _log;

    public ClientDocumentController(
        SqlService sql,
        ClientContext client,
        IConfiguration config,
        AuthorizationGuard guard,
        ILogger<ClientDocumentController> log)
    {
        _sql    = sql;
        _client = client;
        _config = config;
        _guard  = guard;
        _log    = log;
    }

    // ── POST /api/documents/list ─────────────────────────────────────────────
    [HttpPost("list")]
    public async Task<IActionResult> List([FromBody] JsonElement body, CancellationToken ct)
    {
        var (ok, err) = _guard.RequireAuth();
        if (!ok) return Unauthorized(new { ok = false, error = err });

        try
        {
            var rqst = JsonSerializer.Serialize(new
            {
                scope    = "client",
                clientId = _client.ClientId   // always from session, never from body
            });

            var result = await _sql.ExecProcAsync("dbo.usp_DocumentList", "list", rqst, ct: ct);
            return Content(result, "application/json");
        }
        catch (Exception ex)
        {
            _log.LogError(ex, "Client document list failed");
            return StatusCode(500, new { ok = false, error = "Document service error" });
        }
    }

    // ── POST /api/documents ──────────────────────────────────────────────────
    [HttpPost]
    [RequestSizeLimit(52_428_800)]
    public async Task<IActionResult> Upload(
        IFormFile  file,
        [FromForm] string  category,
        [FromForm] string? description = null,
        CancellationToken  ct = default)
    {
        var (ok, err) = _guard.RequireAuth();
        if (!ok) return Unauthorized(new { ok = false, error = err });

        if (file == null || file.Length == 0)
            return BadRequest(new { ok = false, error = "No file provided" });

        try
        {
            byte[] fileBytes;
            using (var ms = new MemoryStream())
            {
                await file.CopyToAsync(ms, ct);
                fileBytes = ms.ToArray();
            }

            var rqst = JsonSerializer.Serialize(new
            {
                docFileName    = file.FileName,
                docMimeType    = file.ContentType,
                docFileSize    = file.Length,
                docCategory    = category,
                docDescription = description,
                docUploadedBy  = _client.Email,
                docScope       = "client",
                docCltId       = _client.ClientId   // injected from session
            });

            _log.LogInformation("[ClientDocs] Upload {FileName} | Client={ClientId}",
                file.FileName, _client.ClientId);

            var result = await ExecUploadAsync(rqst, fileBytes, ct);
            return Content(result, "application/json");
        }
        catch (Exception ex)
        {
            _log.LogError(ex, "Client document upload failed: {FileName}", file?.FileName);
            return StatusCode(500, new { ok = false, error = "Upload failed" });
        }
    }

    // ── GET /api/documents/{id}/download ─────────────────────────────────────
    [HttpGet("{id:long}/download")]
    public async Task<IActionResult> Download(long id, CancellationToken ct = default)
    {
        var (ok, err) = _guard.RequireAuth();
        if (!ok) return Unauthorized(new { ok = false, error = err });

        try
        {
            var cs = _config.GetConnectionString("Sql")
                ?? throw new InvalidOperationException("Missing ConnectionStrings:Sql");

            await using var conn = new SqlConnection(cs);
            await conn.OpenAsync(ct);

            await using var cmd = new SqlCommand("dbo.usp_Document", conn)
            {
                CommandType    = CommandType.StoredProcedure,
                CommandTimeout = 60
            };
            cmd.Parameters.Add(new SqlParameter("@action", SqlDbType.VarChar,  50) { Value = "document.download" });
            cmd.Parameters.Add(new SqlParameter("@rqst",   SqlDbType.NVarChar, -1) { Value =
                JsonSerializer.Serialize(new { docId = id, clientId = _client.ClientId }) });

            await using var reader = await cmd.ExecuteReaderAsync(ct);
            if (!await reader.ReadAsync(ct))
                return NotFound(new { ok = false, error = "Document not found" });

            var fileName = reader.GetString(reader.GetOrdinal("docFileName"));
            var mimeType = reader.GetString(reader.GetOrdinal("docMimeType"));
            var content  = (byte[])reader["docContent"];

            return File(content, mimeType, fileName);
        }
        catch (Exception ex)
        {
            _log.LogError(ex, "Client document download failed: docId={DocId}", id);
            return StatusCode(500, new { ok = false, error = "Download failed" });
        }
    }

    // ── DELETE /api/documents/{id} ───────────────────────────────────────────
    [HttpDelete("{id:long}")]
    public async Task<IActionResult> Delete(long id, CancellationToken ct = default)
    {
        var (ok, err) = _guard.RequireAuth();
        if (!ok) return Unauthorized(new { ok = false, error = err });

        try
        {
            _log.LogInformation("[ClientDocs] Delete docId={DocId} | Client={ClientId}", id, _client.ClientId);

            // Pass clientId so the SP enforces ownership before deleting
            var rqst   = JsonSerializer.Serialize(new { docId = id, clientId = _client.ClientId });
            var result = await _sql.ExecProcAsync("dbo.usp_Document", "document.delete", rqst, ct: ct);
            return Content(result, "application/json");
        }
        catch (Exception ex)
        {
            _log.LogError(ex, "Client document delete failed: docId={DocId}", id);
            return StatusCode(500, new { ok = false, error = "Delete failed" });
        }
    }

    // ─── Upload helper: binary passed separately from JSON rqst ──────────────
    private async Task<string> ExecUploadAsync(string rqst, byte[] fileContent, CancellationToken ct)
    {
        var cs = _config.GetConnectionString("Sql")
            ?? throw new InvalidOperationException("Missing ConnectionStrings:Sql");

        await using var conn = new SqlConnection(cs);
        await conn.OpenAsync(ct);

        await using var cmd = new SqlCommand("dbo.usp_Document", conn)
        {
            CommandType    = CommandType.StoredProcedure,
            CommandTimeout = 60
        };

        cmd.Parameters.Add(new SqlParameter("@action",      SqlDbType.VarChar,  50) { Value = "document.upload" });
        cmd.Parameters.Add(new SqlParameter("@rqst",        SqlDbType.NVarChar, -1) { Value = rqst });
        cmd.Parameters.Add(new SqlParameter("@filecontent", SqlDbType.VarBinary, -1) { Value = fileContent });

        var pResp = new SqlParameter("@resp", SqlDbType.NVarChar, -1)
        {
            Direction = ParameterDirection.Output
        };
        cmd.Parameters.Add(pResp);

        await cmd.ExecuteNonQueryAsync(ct);

        return pResp.Value as string
            ?? JsonSerializer.Serialize(new { ok = false, error = "No response from database" });
    }
}