// Copyright (c) Microsoft. All rights reserved.

namespace Harness.ConsoleReactiveFramework;

/// <summary>
/// Abstract base class for all console UI components. Provides layout properties
/// (position and size) and a <see cref="Render"/> method for drawing to the console.
/// Derive from <see cref="ConsoleReactiveComponent{TProps, TState}"/> instead of this class directly.
/// </summary>
public abstract class ConsoleReactiveComponent
{
    internal ConsoleReactiveComponent()
    {
    }

    /// <summary>Gets or sets the 1-based column position of the component.</summary>
    public int X { get; set; }

    /// <summary>Gets or sets the 1-based row position of the component.</summary>
    public int Y { get; set; }

    /// <summary>Gets or sets the width of the component in columns.</summary>
    public int Width { get; set; }

    /// <summary>Gets or sets the height of the component in rows.</summary>
    public int Height { get; set; }

    /// <summary>Renders the component to the console at its current position.</summary>
    public abstract void Render();
}

/// <summary>
/// Generic base class for console UI components with typed props and state.
/// Props represent externally supplied configuration; state represents internal mutable data.
/// </summary>
/// <typeparam name="TProps">The type of the component's props (external configuration).</typeparam>
/// <typeparam name="TState">The type of the component's internal state.</typeparam>
public abstract class ConsoleReactiveComponent<TProps, TState> : ConsoleReactiveComponent
    where TProps : ConsoleReactiveProps
    where TState : ConsoleReactiveState
{
    private readonly object _renderLock = new();
    private TProps? _lastRenderedProps;
    private TState? _lastRenderedState;

    /// <summary>Gets or sets the component's props (external configuration).</summary>
    public TProps? Props { get; set; }

    /// <summary>Gets or sets the component's internal state.</summary>
    protected TState? State { get; set; }

    /// <summary>
    /// Updates the component's state and triggers a re-render.
    /// </summary>
    /// <param name="newState">The new state value.</param>
    public void SetState(TState newState)
    {
        this.State = newState;
        this.Render();
    }

    /// <summary>
    /// Renders the component using the current props and state.
    /// Uses a lock to prevent concurrent renders from multiple sources.
    /// Skips rendering if neither props nor state have changed since the last render.
    /// </summary>
    public override void Render()
    {
        lock (this._renderLock)
        {
            if (this.Props is null)
            {
                return;
            }

            if (ReferenceEquals(this.Props, this._lastRenderedProps)
                && ReferenceEquals(this.State, this._lastRenderedState))
            {
                return;
            }

            this.RenderCore(this.Props, this.State!);

            this._lastRenderedProps = this.Props;
            this._lastRenderedState = this.State;
        }
    }

    /// <summary>
    /// Called by <see cref="Render"/> to perform the actual rendering. Override this in derived classes.
    /// </summary>
    /// <param name="props">The current props.</param>
    /// <param name="state">The current state.</param>
    public abstract void RenderCore(TProps props, TState state);
}

/// <summary>
/// Base record for component props. Provides an optional <see cref="Children"/> collection
/// for composing child components.
/// </summary>
public record ConsoleReactiveProps
{
    /// <summary>Gets the child components to render within this component.</summary>
    public IReadOnlyList<ConsoleReactiveComponent> Children { get; init; } = [];
}

/// <summary>
/// Base record for component state.
/// </summary>
public record ConsoleReactiveState;