using System;
using System.ComponentModel;
using System.IO;
using System.Linq;
using System.Windows.Forms;
using BulkArchiveMailer.Core;
using Outlook = Microsoft.Office.Interop.Outlook;

namespace BulkArchiveMailer.AddIn.UI
{
    /// <summary>
    /// Scans the configured archive folder, shows one row per login (plus
    /// unrecognized files) in a grid, and sends the checked rows through
    /// MailSender. This is the only form that actually touches Outlook
    /// COM (via the Outlook.Application passed into its constructor) or
    /// writes to the send log.
    /// </summary>
    public partial class PreviewForm : Form
    {
        private readonly Outlook.Application outlookApplication;

        private AppSettingsData settings;
        private SendLogStore sendLog;
        private string signatureHtml;
        private BindingList<PreviewRow> rows;

        public PreviewForm(Outlook.Application outlookApplication)
        {
            InitializeComponent();
            this.outlookApplication = outlookApplication ?? throw new ArgumentNullException(nameof(outlookApplication));
            Load += PreviewForm_Load;
        }

        private void PreviewForm_Load(object sender, EventArgs e)
        {
            try
            {
                settings = AppSettings.Load();
            }
            catch (Exception ex)
            {
                MessageBox.Show(this, "Не удалось прочитать настройки: " + ex.ToString(), "BulkArchiveMailer", MessageBoxButtons.OK, MessageBoxIcon.Error);
                Close();
                return;
            }

            chkTestMode.Checked = settings.TestModeDefault;

            signatureHtml = ResolveSignatureHtml();
            lblSignatureWarning.Visible = string.IsNullOrEmpty(signatureHtml);

            RunScan();
        }

        private string ResolveSignatureHtml()
        {
            try
            {
                if (!string.IsNullOrWhiteSpace(settings.SignatureHtmlPath))
                {
                    return File.Exists(settings.SignatureHtmlPath) ? File.ReadAllText(settings.SignatureHtmlPath) : null;
                }

                return SignatureReader.TryAutoDetectSignatureHtml(outlookApplication);
            }
            catch
            {
                return null; // never block preview over a signature problem
            }
        }

        private void RunScan()
        {
            if (string.IsNullOrWhiteSpace(settings.ArchiveFolder) || !Directory.Exists(settings.ArchiveFolder))
            {
                MessageBox.Show(
                    this,
                    "Папка с архивами не настроена или не существует:\n" + settings.ArchiveFolder,
                    "BulkArchiveMailer",
                    MessageBoxButtons.OK,
                    MessageBoxIcon.Error);
                Close();
                return;
            }

            var logPath = Path.Combine(settings.ArchiveFolder, "send-log.csv");
            sendLog = new SendLogStore(logPath);

            var templates = settings.ToTemplateSet();
            var scan = ArchiveScanner.Scan(settings.ArchiveFolder, settings.EmailDomain, templates, sendLog);

            rows = new BindingList<PreviewRow>(scan.AllRows.Select(job => new PreviewRow(job)).ToList());
            grid.DataSource = rows;

            UpdateSummaryLabel();
        }

        private void ApplyRowStyles()
        {
            foreach (DataGridViewRow row in grid.Rows)
            {
                if (!(row.DataBoundItem is PreviewRow previewRow))
                {
                    continue;
                }

                row.Cells[colSelect.Index].ReadOnly = !previewRow.Job.IsSelectable;

                switch (previewRow.Job.Status)
                {
                    case SendStatus.Error:
                        row.DefaultCellStyle.BackColor = System.Drawing.Color.MistyRose;
                        break;
                    case SendStatus.Skipped:
                        row.DefaultCellStyle.BackColor = System.Drawing.Color.WhiteSmoke;
                        row.DefaultCellStyle.ForeColor = System.Drawing.Color.Gray;
                        break;
                    case SendStatus.AlreadySent:
                        row.DefaultCellStyle.BackColor = System.Drawing.Color.LightYellow;
                        break;
                    default:
                        row.DefaultCellStyle.BackColor = grid.DefaultCellStyle.BackColor;
                        row.DefaultCellStyle.ForeColor = grid.DefaultCellStyle.ForeColor;
                        break;
                }
            }
        }

        private void UpdateSummaryLabel()
        {
            if (rows == null)
            {
                // Can be invoked before RunScan() ever ran - most notably,
                // WinForms fires DataGridView.CellValueChanged as a side
                // effect of DataGridViewColumn.HeaderText assignments in
                // InitializeComponent(), i.e. before the constructor (and
                // therefore RunScan()) has had a chance to populate `rows`.
                // Nothing to summarize yet in that case.
                return;
            }

            var ready = rows.Count(r => r.Job.Status == SendStatus.Ready);
            var already = rows.Count(r => r.Job.Status == SendStatus.AlreadySent);
            var errors = rows.Count(r => r.Job.Status == SendStatus.Error);
            var skipped = rows.Count(r => r.Job.Status == SendStatus.Skipped);
            var checkedCount = rows.Count(r => r.IsChecked);

            lblSummary.Text = $"Готово: {ready}   Уже отправлено: {already}   Ошибки: {errors}   Пропущено: {skipped}   |   Отмечено к отправке: {checkedCount}";
        }

        private void grid_DataBindingComplete(object sender, DataGridViewBindingCompleteEventArgs e)
        {
            ApplyRowStyles();
            UpdateSummaryLabel();
        }

        private void grid_CurrentCellDirtyStateChanged(object sender, EventArgs e)
        {
            if (grid.IsCurrentCellDirty && grid.CurrentCell is DataGridViewCheckBoxCell)
            {
                grid.CommitEdit(DataGridViewDataErrorContexts.Commit);
            }
        }

        private void grid_CellValueChanged(object sender, DataGridViewCellEventArgs e)
        {
            UpdateSummaryLabel();
        }

        private void btnRescan_Click(object sender, EventArgs e)
        {
            RunScan();
        }

        private void btnSettings_Click(object sender, EventArgs e)
        {
            using (var settingsForm = new SettingsForm(outlookApplication))
            {
                settingsForm.ShowDialog(this);
            }

            // Regardless of DialogResult (OK or Cancel), reload settings and
            // rescan so a changed archive folder, domain, or templates are
            // reflected immediately without a separate "Пересканировать"
            // click. A closed-without-saving dialog just reloads the same
            // settings again, which is harmless.
            try
            {
                settings = AppSettings.Load();
            }
            catch (Exception ex)
            {
                MessageBox.Show(this, "Не удалось прочитать настройки: " + ex.ToString(), "BulkArchiveMailer", MessageBoxButtons.OK, MessageBoxIcon.Error);
                return;
            }

            signatureHtml = ResolveSignatureHtml();
            lblSignatureWarning.Visible = string.IsNullOrEmpty(signatureHtml);

            RunScan();
        }

        private void btnCheckAllReady_Click(object sender, EventArgs e)
        {
            foreach (var row in rows)
            {
                if (row.Job.IsSelectable)
                {
                    row.IsChecked = true;
                }
            }

            grid.Refresh();
            UpdateSummaryLabel();
        }

        private void btnUncheckAll_Click(object sender, EventArgs e)
        {
            foreach (var row in rows)
            {
                row.IsChecked = false;
            }

            grid.Refresh();
            UpdateSummaryLabel();
        }

        private void btnClose_Click(object sender, EventArgs e)
        {
            Close();
        }

        private void btnSend_Click(object sender, EventArgs e)
        {
            var toSend = rows.Where(r => r.IsChecked && r.Job.IsSelectable).ToList();
            if (toSend.Count == 0)
            {
                MessageBox.Show(this, "Не выбрано ни одной строки для отправки.", "BulkArchiveMailer", MessageBoxButtons.OK, MessageBoxIcon.Information);
                return;
            }

            var testMode = chkTestMode.Checked;
            var confirmText = testMode
                ? $"Сохранить {toSend.Count} писем в Черновики (тестовый режим, реальная отправка НЕ произойдёт)?"
                : $"Отправить {toSend.Count} писем? Это реальная отправка получателям.";
            if (MessageBox.Show(this, confirmText, "Подтверждение", MessageBoxButtons.YesNo, MessageBoxIcon.Question) != DialogResult.Yes)
            {
                return;
            }

            btnSend.Enabled = false;
            btnRescan.Enabled = false;
            progressSend.Minimum = 0;
            progressSend.Maximum = toSend.Count;
            progressSend.Value = 0;

            var mailSender = new MailSender(outlookApplication, signatureHtml, settings.FromAccountSmtpAddress);
            var sentCount = 0;
            var failedCount = 0;

            foreach (var row in toSend)
            {
                lblProgressStatus.Text = $"Обработка: {row.Job.Email} ({row.Job.KindDisplay})...";
                // No async/await here on purpose: Outlook COM objects are
                // STA-thread-affine, and MailSender.SendOne must run on
                // this UI thread. DoEvents keeps the form responsive
                // (progress bar, ability to see the current item) during
                // what is otherwise a synchronous per-item loop.
                Application.DoEvents();

                var outcome = mailSender.SendOne(row.Job, testMode);

                try
                {
                    sendLog.Append(new SendLogEntry
                    {
                        TimestampUtc = DateTime.UtcNow,
                        Login = row.Job.Login,
                        Email = row.Job.Email,
                        Kind = row.Job.Kind ?? default,
                        ArchivePath = row.Job.ArchivePath ?? "",
                        FileSha256 = row.Job.FileSha256 ?? "",
                        Status = outcome.Success ? (testMode ? SendLogStatus.Draft : SendLogStatus.Sent) : SendLogStatus.Failed,
                        Error = outcome.Success ? "" : outcome.ErrorMessage,
                    });
                }
                catch (Exception logEx)
                {
                    // A logging failure must not be confused with a send
                    // failure, but it also must not silently disappear -
                    // surface it in the comment column.
                    row.ResultText = (outcome.Success ? "Отправлено, но" : "Ошибка отправки, и") + " не удалось записать в журнал: " + logEx.Message;
                    row.IsChecked = false;
                    grid.Refresh();
                    continue;
                }

                if (outcome.Success)
                {
                    sentCount++;
                    row.ResultText = testMode ? "Сохранено в Черновики" : "Отправлено";
                }
                else
                {
                    failedCount++;
                    row.ResultText = "Ошибка: " + outcome.ErrorMessage;
                }

                row.IsChecked = false;
                progressSend.Value++;
                grid.Refresh();
            }

            btnSend.Enabled = true;
            btnRescan.Enabled = true;
            lblProgressStatus.Text = "Готово.";
            UpdateSummaryLabel();

            MessageBox.Show(
                this,
                $"Отправлено/сохранено: {sentCount}\nОшибок: {failedCount}\n\nЖурнал: {sendLog.CsvPath}",
                "Массовая рассылка — итог",
                MessageBoxButtons.OK,
                MessageBoxIcon.Information);
        }

        /// <summary>
        /// UI-only wrapper around a Core SendJob: adds the checkbox state
        /// and post-send result text, neither of which belong in the
        /// portable Core model.
        /// </summary>
        private sealed class PreviewRow
        {
            public PreviewRow(SendJob job)
            {
                Job = job;
                // AlreadySent starts unchecked by default (per spec) but
                // remains selectable if the operator wants to resend it
                // anyway (e.g. recipient claims they never got it).
                IsChecked = job.Status == SendStatus.Ready;
            }

            public SendJob Job { get; }

            public bool IsChecked { get; set; }

            public string ResultText { get; set; } = "";

            public string Login => Job.Login;

            public string Email => Job.Email;

            public string KindDisplay => Job.KindDisplay;

            public string FileName => Job.FileName;

            public string StatusDisplay => ToRussian(Job.Status);

            public string Comment => !string.IsNullOrEmpty(ResultText) ? ResultText : (Job.ErrorMessage ?? "");

            private static string ToRussian(SendStatus status)
            {
                switch (status)
                {
                    case SendStatus.Ready:
                        return "Готово";
                    case SendStatus.AlreadySent:
                        return "Уже отправлено";
                    case SendStatus.Error:
                        return "Ошибка";
                    case SendStatus.Skipped:
                        return "Пропущено";
                    default:
                        return status.ToString();
                }
            }
        }
    }
}