using System.Text.Json;

namespace Agent.Core.Tools;

public sealed class InternalToolDispatcher(IToolPolicyEngine policy, IInternalToolBackend backend)
{
    public Task BeginTaskAsync(Guid taskId, Guid sessionId, CancellationToken cancellationToken) => backend.BeginTaskAsync(taskId, sessionId, cancellationToken);
    public Task EndTaskAsync(Guid taskId, bool success, CancellationToken cancellationToken) => backend.EndTaskAsync(taskId, success, cancellationToken);

    public async Task<ToolExecutionResult> DispatchAsync(Guid taskId, string toolName, JsonElement arguments, CancellationToken cancellationToken)
    {
        InternalToolValidator.Validate(toolName, arguments);
        ToolPolicyDecision decision = policy.Evaluate(toolName, arguments);
        if (!decision.Allowed) return new(false, decision.Reason, false, $"policy:{toolName}:{decision.Reason}", RetryAllowed: false,
            ErrorCode: "policy.tool_denied", ErrorCategory: "policy", Resolution: "Review the enabled Internal Tool policy.");
        return await backend.ExecuteAsync(taskId, toolName, arguments, cancellationToken).ConfigureAwait(false);
    }
}

public sealed class FakeInternalToolBackend : IInternalToolBackend
{
    private readonly List<(string Name, JsonElement Arguments)> _calls = [];
    public IReadOnlyList<(string Name, JsonElement Arguments)> Calls => _calls;
    public Task<ToolExecutionResult> ExecuteAsync(Guid taskId, string toolName, JsonElement arguments, CancellationToken cancellationToken)
    {
        _calls.Add((toolName, arguments.Clone()));
        bool effect = toolName is "file_edit" or "process_run" or "dir";
        return Task.FromResult(new ToolExecutionResult(true, "fake-ok", effect));
    }
}