using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using TaskTracker.Core.Entities;
using TaskTracker.Core.Enums;
using TaskTracker.Core.Interfaces;

namespace TaskTracker.Api.Pages;

public record ColumnViewModel(WorkTaskStatus Status, string Label, string Color, List<WorkTask> Tasks);

[IgnoreAntiforgeryToken]
public class BoardModel : PageModel
{
    private readonly ITaskRepository _taskRepo;

    public BoardModel(ITaskRepository taskRepo)
    {
        _taskRepo = taskRepo;
    }

    public List<ColumnViewModel> Columns { get; set; } = new();
    public string? ActiveCategory { get; set; }
    public bool HasSubtasksFilter { get; set; }
    public List<string> AllCategories { get; set; } = new();

    private static readonly (WorkTaskStatus Status, string Label, string Color)[] ColumnConfig =
    [
        (WorkTaskStatus.Pending, "Pending", "#64748b"),
        (WorkTaskStatus.Active, "Active", "#3b82f6"),
        (WorkTaskStatus.Paused, "Paused", "#eab308"),
        (WorkTaskStatus.Completed, "Completed", "#22c55e"),
    ];

    public static readonly Dictionary<string, string> CategoryColors = new()
    {
        ["Development"] = "#6366f1",
        ["Research"] = "#06b6d4",
        ["Communication"] = "#8b5cf6",
        ["DevOps"] = "#f97316",
        ["Documentation"] = "#14b8a6",
        ["Design"] = "#ec4899",
        ["Testing"] = "#3b82f6",
        ["General"] = "#64748b",
        ["Email"] = "#f59e0b",
        ["Engineering"] = "#6366f1",
        ["LaserCutting"] = "#ef4444",
        ["Unknown"] = "#475569",
    };

    public static string GetCategoryColor(string? category)
    {
        if (string.IsNullOrEmpty(category)) return CategoryColors["Unknown"];
        return CategoryColors.TryGetValue(category, out var color) ? color : CategoryColors["Unknown"];
    }

    public static string FormatElapsed(DateTime? startedAt, DateTime? completedAt)
    {
        if (startedAt is null) return "--";
        var start = startedAt.Value;
        var end = completedAt ?? DateTime.UtcNow;
        var mins = (int)(end - start).TotalMinutes;
        if (mins < 60) return $"{mins}m";
        var hours = mins / 60;
        var remainder = mins % 60;
        if (hours < 24) return $"{hours}h {remainder}m";
        var days = hours / 24;
        return $"{days}d {hours % 24}h";
    }

    public async Task<IActionResult> OnGetAsync(string? category, bool hasSubtasks = false)
    {
        ActiveCategory = category;
        HasSubtasksFilter = hasSubtasks;

        await LoadBoardDataAsync();

        return Page();
    }

    public async Task<IActionResult> OnPutStartAsync(int id)
    {
        var task = await _taskRepo.GetByIdAsync(id);
        if (task is null) return NotFound();

        var active = await _taskRepo.GetActiveTaskAsync();
        if (active is not null && active.Id != id)
        {
            active.Status = WorkTaskStatus.Paused;
            await _taskRepo.UpdateAsync(active);
        }

        task.Status = WorkTaskStatus.Active;
        task.StartedAt ??= DateTime.UtcNow;
        await _taskRepo.UpdateAsync(task);

        return await ReturnBoardContentAsync();
    }

    public async Task<IActionResult> OnPutPauseAsync(int id)
    {
        var task = await _taskRepo.GetByIdAsync(id);
        if (task is null) return NotFound();

        task.Status = WorkTaskStatus.Paused;
        await _taskRepo.UpdateAsync(task);

        return await ReturnBoardContentAsync();
    }

    public async Task<IActionResult> OnPutResumeAsync(int id)
    {
        var active = await _taskRepo.GetActiveTaskAsync();
        if (active is not null)
        {
            active.Status = WorkTaskStatus.Paused;
            await _taskRepo.UpdateAsync(active);
        }

        var task = await _taskRepo.GetByIdAsync(id);
        if (task is null) return NotFound();

        task.Status = WorkTaskStatus.Active;
        task.StartedAt ??= DateTime.UtcNow;
        await _taskRepo.UpdateAsync(task);

        return await ReturnBoardContentAsync();
    }

    public async Task<IActionResult> OnPutCompleteAsync(int id)
    {
        var task = await _taskRepo.GetByIdAsync(id);
        if (task is null) return NotFound();

        var incompleteSubtasks = task.SubTasks
            .Count(st => st.Status != WorkTaskStatus.Completed && st.Status != WorkTaskStatus.Abandoned);
        if (incompleteSubtasks > 0)
        {
            return BadRequest($"Cannot complete: {incompleteSubtasks} subtask(s) still incomplete.");
        }

        task.Status = WorkTaskStatus.Completed;
        task.CompletedAt = DateTime.UtcNow;
        await _taskRepo.UpdateAsync(task);

        return await ReturnBoardContentAsync();
    }

    public async Task<IActionResult> OnDeleteAbandonAsync(int id)
    {
        await _taskRepo.DeleteAsync(id);
        return await ReturnBoardContentAsync();
    }

    public async Task<IActionResult> OnPostCreateTaskAsync(string title, string? category)
    {
        if (string.IsNullOrWhiteSpace(title))
            return BadRequest("Title is required.");

        var task = new WorkTask
        {
            Title = title.Trim(),
            Category = category,
            Status = WorkTaskStatus.Pending,
        };
        await _taskRepo.CreateAsync(task);

        return await ReturnBoardContentAsync();
    }

    private async Task<IActionResult> ReturnBoardContentAsync()
    {
        await LoadBoardDataAsync();
        return Partial("Partials/_KanbanBoard", this);
    }

    private async Task LoadBoardDataAsync()
    {
        // Load all tasks with subtasks for category list
        var allTasks = await _taskRepo.GetAllAsync(includeSubTasks: true);

        // Collect all distinct categories from all tasks (unfiltered)
        AllCategories = allTasks
            .Where(t => !string.IsNullOrEmpty(t.Category))
            .Select(t => t.Category!)
            .Distinct()
            .OrderBy(c => c)
            .ToList();

        // Filter to top-level only
        var tasks = allTasks.Where(t => t.ParentTaskId == null).ToList();

        // Apply category filter
        if (!string.IsNullOrEmpty(ActiveCategory))
        {
            tasks = tasks.Where(t =>
                string.Equals(t.Category, ActiveCategory, StringComparison.OrdinalIgnoreCase)).ToList();
        }

        // Apply hasSubtasks filter
        if (HasSubtasksFilter)
        {
            tasks = tasks.Where(t => t.SubTasks.Count > 0).ToList();
        }

        // Group by status into columns
        var tasksByStatus = tasks.ToLookup(t => t.Status);

        Columns = ColumnConfig
            .Select(cfg => new ColumnViewModel(
                cfg.Status,
                cfg.Label,
                cfg.Color,
                tasksByStatus[cfg.Status].ToList()))
            .ToList();
    }
}