using System.Collections.Generic;
using System.Linq;
using AcDream.UI.Abstractions.Input;

namespace AcDream.UI.Abstractions.Panels.Settings;

/// <summary>
/// In-game Settings panel — F11 toggle (or View → Settings on the main
/// menu bar). Hidden by default. Tabbed: Keybinds (Phase K), then
/// Display / Audio / Gameplay / Chat / Character (filling in over the
/// L.x sub-phases).
///
/// <para>
/// Top of the panel: Save / Cancel / Reset-all action buttons (global
/// across all tabs). When <see cref="SettingsVM.PendingConflict"/> is
/// non-null, a confirmation prompt is rendered above those buttons
/// (Yes — Reassign / No — Keep existing).
/// </para>
///
/// <para>
/// Below the action row a tab bar selects between the six categories.
/// Only the Keybinds tab is implemented today; the other five render
/// "Coming soon" placeholders so the structure the user approved in the
/// design brainstorm is visible immediately.
/// </para>
/// </summary>
public sealed class SettingsPanel : IPanel
{
    private readonly SettingsVM _vm;

    public SettingsPanel(SettingsVM vm)
    {
        _vm = vm ?? throw new System.ArgumentNullException(nameof(vm));
    }

    /// <inheritdoc />
    public string Id => "acdream.settings";

    /// <inheritdoc />
    public string Title => "Settings";

    /// <inheritdoc />
    /// <remarks>Hidden by default — opened via F11 / View menu.</remarks>
    public bool IsVisible { get; set; } = false;

    /// <inheritdoc />
    public void Render(PanelContext ctx, IPanelRenderer renderer)
    {
        if (!renderer.Begin(Title))
        {
            renderer.End();
            return;
        }

        // Conflict prompt — modal-ish row at top of the panel.
        if (_vm.PendingConflict is { } conflict)
        {
            renderer.TextWrapped(
                $"'{ChordLabel(conflict.NewChord)}' is already bound to "
                + $"{conflict.ConflictingAction}. Reassign it to "
                + $"{conflict.NewAction}?");
            if (renderer.Button("Yes — Reassign")) _vm.ResolveConflict(replace: true);
            renderer.SameLine();
            if (renderer.Button("No — Keep existing")) _vm.ResolveConflict(replace: false);
            renderer.Separator();
        }

        // Top action buttons. Global across all tabs.
        if (renderer.Button("Save changes")) _vm.Save();
        renderer.SameLine();
        if (renderer.Button("Cancel changes")) _vm.Cancel();
        renderer.SameLine();
        if (renderer.Button("Reset all to retail defaults")) _vm.ResetAllToDefaults();

        renderer.Separator();

        if (renderer.BeginTabBar("settings.tabs"))
        {
            if (renderer.BeginTabItem("Keybinds"))
            {
                RenderKeybindsTab(renderer);
                renderer.EndTabItem();
            }
            if (renderer.BeginTabItem("Display"))
            {
                RenderDisplayTab(renderer);
                renderer.EndTabItem();
            }
            if (renderer.BeginTabItem("Audio"))
            {
                RenderPlaceholder(renderer, "Audio");
                renderer.EndTabItem();
            }
            if (renderer.BeginTabItem("Gameplay"))
            {
                RenderPlaceholder(renderer, "Gameplay");
                renderer.EndTabItem();
            }
            if (renderer.BeginTabItem("Chat"))
            {
                RenderPlaceholder(renderer, "Chat");
                renderer.EndTabItem();
            }
            if (renderer.BeginTabItem("Character"))
            {
                RenderPlaceholder(renderer, "Character");
                renderer.EndTabItem();
            }
            renderer.EndTabBar();
        }

        renderer.End();
    }

    /// <summary>
    /// Render the Keybinds tab — eight collapsing-header sections matching
    /// the retail keymap categories. Phase K shipped this content; the
    /// only thing that changed is the wrapping tab item.
    /// </summary>
    private void RenderKeybindsTab(IPanelRenderer renderer)
    {
        RenderSection(renderer, "Movement", new[]
        {
            InputAction.MovementForward, InputAction.MovementBackup,
            InputAction.MovementTurnLeft, InputAction.MovementTurnRight,
            InputAction.MovementStrafeLeft, InputAction.MovementStrafeRight,
            InputAction.MovementJump, InputAction.MovementStop,
            InputAction.MovementWalkMode, InputAction.MovementRunLock,
        });
        RenderSection(renderer, "Postures", new[]
        {
            InputAction.Ready, InputAction.Sitting,
            InputAction.Crouch, InputAction.Sleeping,
        });
        RenderSection(renderer, "Camera", new[]
        {
            InputAction.CameraActivateAlternateMode, InputAction.CameraInstantMouseLook,
            InputAction.CameraRotateLeft, InputAction.CameraRotateRight,
            InputAction.CameraRotateUp, InputAction.CameraRotateDown,
            InputAction.CameraMoveToward, InputAction.CameraMoveAway,
            InputAction.CameraViewDefault, InputAction.CameraViewFirstPerson,
            InputAction.CameraViewLookDown, InputAction.CameraViewMapMode,
        });
        RenderSection(renderer, "Combat", new[]
        {
            InputAction.CombatToggleCombat,
            InputAction.CombatDecreaseAttackPower, InputAction.CombatIncreaseAttackPower,
            InputAction.CombatLowAttack, InputAction.CombatMediumAttack, InputAction.CombatHighAttack,
            InputAction.CombatAimLow, InputAction.CombatAimMedium, InputAction.CombatAimHigh,
            InputAction.CombatPrevSpellTab, InputAction.CombatNextSpellTab,
            InputAction.CombatPrevSpell, InputAction.CombatNextSpell, InputAction.CombatCastCurrentSpell,
        });
        RenderSection(renderer, "UI panels", new[]
        {
            InputAction.ToggleHelp, InputAction.ToggleAllegiancePanel,
            InputAction.ToggleFellowshipPanel, InputAction.ToggleSpellbookPanel,
            InputAction.ToggleSpellComponentsPanel, InputAction.ToggleAttributesPanel,
            InputAction.ToggleSkillsPanel, InputAction.ToggleWorldPanel,
            InputAction.ToggleOptionsPanel, InputAction.ToggleInventoryPanel,
            InputAction.SelectionExamine, InputAction.UseSelected,
            InputAction.EscapeKey, InputAction.LOGOUT,
        });
        RenderSection(renderer, "Chat", new[]
        {
            InputAction.ToggleChatEntry, InputAction.EnterChatMode,
            InputAction.ToggleFloatingChatWindow1, InputAction.ToggleFloatingChatWindow2,
            InputAction.ToggleFloatingChatWindow3, InputAction.ToggleFloatingChatWindow4,
        });
        RenderSection(renderer, "Hotbar", new[]
        {
            InputAction.UseQuickSlot_1, InputAction.UseQuickSlot_2, InputAction.UseQuickSlot_3,
            InputAction.UseQuickSlot_4, InputAction.UseQuickSlot_5, InputAction.UseQuickSlot_6,
            InputAction.UseQuickSlot_7, InputAction.UseQuickSlot_8, InputAction.UseQuickSlot_9,
            InputAction.CreateShortcut,
        });
        RenderSection(renderer, "Emotes", new[]
        {
            InputAction.Cry, InputAction.Laugh, InputAction.Wave,
            InputAction.Cheer, InputAction.PointState,
        });
    }

    /// <summary>
    /// Placeholder content shown for tabs whose implementation is still
    /// pending. Reads as "Coming soon" plus a note about which sub-phase
    /// is expected to fill it in.
    /// </summary>
    private static void RenderPlaceholder(IPanelRenderer renderer, string tabName)
    {
        renderer.TextWrapped($"{tabName} settings coming soon.");
        renderer.Spacing();
        renderer.TextWrapped(
            "This tab is part of the staged Settings interface rollout. "
            + "Build order: Display → Audio → Gameplay → Chat → Character.");
    }

    /// <summary>
    /// Render the Display tab — resolution / fullscreen / vsync /
    /// FOV / gamma / show-FPS. FOV + Gamma are live-preview sliders;
    /// the others apply on Save (matches the brainstorm UX agreement —
    /// resolution change live would be too jarring).
    /// </summary>
    private void RenderDisplayTab(IPanelRenderer renderer)
    {
        var d = _vm.DisplayDraft;

        // Resolution dropdown. Index falls back to the highest available
        // option when the persisted resolution isn't one of the presets
        // (e.g. user hand-edited settings.json with a non-standard size).
        var resolutions = DisplaySettings.AvailableResolutions.ToArray();
        int idx = System.Array.IndexOf(resolutions, d.Resolution);
        if (idx < 0) idx = resolutions.Length - 1;
        if (renderer.Combo("Resolution", ref idx, resolutions))
            _vm.SetDisplay(d with { Resolution = resolutions[idx] });

        bool fullscreen = d.Fullscreen;
        if (renderer.Checkbox("Fullscreen", ref fullscreen))
            _vm.SetDisplay(d with { Fullscreen = fullscreen });

        bool vsync = d.VSync;
        if (renderer.Checkbox("V-Sync", ref vsync))
            _vm.SetDisplay(d with { VSync = vsync });

        float fov = d.FieldOfView;
        if (renderer.SliderFloat("Field of View", ref fov, 30f, 120f))
            _vm.SetDisplay(d with { FieldOfView = fov });

        float gamma = d.Gamma;
        if (renderer.SliderFloat("Gamma", ref gamma, 0.5f, 2.0f))
            _vm.SetDisplay(d with { Gamma = gamma });

        bool showFps = d.ShowFps;
        if (renderer.Checkbox("Show FPS", ref showFps))
            _vm.SetDisplay(d with { ShowFps = showFps });

        renderer.Spacing();
        renderer.TextWrapped(
            "Resolution / Fullscreen / V-Sync apply on Save. FOV + Gamma "
            + "preview live as you drag; Cancel reverts to the saved value.");
    }

    private void RenderSection(IPanelRenderer renderer, string label, InputAction[] actions)
    {
        // Movement defaults open; other sections collapsed for first-run UX.
        bool defaultOpen = label == "Movement";
        if (!renderer.CollapsingHeader(label, defaultOpen))
            return;

        foreach (var action in actions)
        {
            renderer.Text(action.ToString());
            renderer.SameLine();

            // Current binding(s) summary.
            var binds = _vm.Draft.ForAction(action).ToList();
            string summary = binds.Count == 0
                ? "(unbound)"
                : string.Join(", ", binds.Select(b => ChordLabel(b.Chord)));
            renderer.Text(summary);
            renderer.SameLine();

            // Rebind button — when a rebind is in progress for THIS
            // action, the label changes to a "press a key..." prompt.
            // The "##{action}" suffix gives ImGui a stable per-row id
            // so multiple "Rebind" buttons don't collide.
            string buttonLabel = (_vm.RebindInProgress == action)
                ? $"Press a key... (Esc to cancel)##{action}"
                : $"Rebind##{action}";
            if (renderer.Button(buttonLabel))
            {
                if (binds.Count > 0 && _vm.RebindInProgress is null)
                    _vm.BeginRebind(action, binds[0]);
            }
            renderer.SameLine();
            if (renderer.Button($"Reset##{action}"))
                _vm.ResetActionToDefault(action);
        }
    }

    /// <summary>
    /// Render a chord as <c>"Shift+Ctrl+A"</c> / <c>"W"</c> / etc. for the
    /// row summary + conflict prompt. Joins held modifiers with <c>+</c>
    /// then the trigger key name.
    /// </summary>
    private static string ChordLabel(KeyChord chord)
    {
        var parts = new List<string>();
        if ((chord.Modifiers & ModifierMask.Shift) != 0) parts.Add("Shift");
        if ((chord.Modifiers & ModifierMask.Ctrl)  != 0) parts.Add("Ctrl");
        if ((chord.Modifiers & ModifierMask.Alt)   != 0) parts.Add("Alt");
        if ((chord.Modifiers & ModifierMask.Win)   != 0) parts.Add("Win");
        parts.Add(chord.Key.ToString());
        return string.Join("+", parts);
    }
}