using System.Text;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using JobTrackerApi.Data;

namespace JobTrackerApi.Controllers
{
    [ApiController]
    [Route("api/export")]
    public class ExportController : ControllerBase
    {
        private readonly JobTrackerContext _db;

        public ExportController(JobTrackerContext db)
        {
            _db = db;
        }

        [HttpGet("jobs")]
        public async Task<IActionResult> ExportJobs(
            [FromQuery] string format = "json",
            [FromQuery] bool includeDeleted = false,
            CancellationToken cancellationToken = default
        )
        {
            var query = _db.JobApplications
                .AsNoTracking()
                .Include(j => j.Company)
                .AsQueryable();

            if (!includeDeleted) query = query.Where(j => !j.IsDeleted);

            var jobs = await query
                .OrderByDescending(j => j.DateApplied)
                .ToListAsync(cancellationToken);

            var stamp = DateTime.Now.ToString("yyyy-MM-dd");

            if (string.Equals(format, "csv", StringComparison.OrdinalIgnoreCase))
            {
                static string Esc(string? s)
                {
                    s ??= "";
                    var needs = s.Contains(',') || s.Contains('"') || s.Contains('\n') || s.Contains('\r');
                    var q = s.Replace("\"", "\"\"");
                    return needs ? $"\"{q}\"" : q;
                }

                var sb = new StringBuilder();
                sb.AppendLine(string.Join(",",
                    "Company",
                    "CompanyLocation",
                    "CompanySource",
                    "JobTitle",
                    "Status",
                    "DateApplied",
                    "Location",
                    "Salary",
                    "NextAction",
                    "FollowUpAt",
                    "JobUrl",
                    "Notes",
                    "CoverLetterText"
                ));

                foreach (var j in jobs)
                {
                    sb.AppendLine(string.Join(",",
                        Esc(j.Company?.Name),
                        Esc(j.Company?.Location),
                        Esc(j.Company?.Source),
                        Esc(j.JobTitle),
                        Esc(j.Status),
                        Esc(j.DateApplied.ToString("o")),
                        Esc(j.Location),
                        Esc(j.Salary),
                        Esc(j.NextAction),
                        Esc(j.FollowUpAt?.ToString("o")),
                        Esc(j.JobUrl),
                        Esc(j.Notes),
                        Esc(j.CoverLetterText)
                    ));
                }

                return File(Encoding.UTF8.GetBytes(sb.ToString()), "text/csv", $"job-tracker-export-{stamp}.csv");
            }

            return File(System.Text.Json.JsonSerializer.SerializeToUtf8Bytes(jobs), "application/json", $"job-tracker-export-{stamp}.json");
        }
    }
}