using System.Collections.Generic;
using System.Linq;

using AIStudio.Provider;

namespace AIStudio.Tools.ToolCallingSystem;

public static class ToolSelectionRules
{
    public const int MAX_TOOL_CALLS = 15;
    public const string WEB_SEARCH_TOOL_ID = "web_search";
    public const string READ_WEB_PAGE_TOOL_ID = "read_web_page";

    public static HashSet<string> NormalizeSelection(IEnumerable<string> selectedToolIds)
    {
        var normalized = selectedToolIds.ToHashSet(StringComparer.Ordinal);
        if (normalized.Contains(WEB_SEARCH_TOOL_ID))
            normalized.Add(READ_WEB_PAGE_TOOL_ID);

        return normalized;
    }

    public static bool IsRequiredBySelectedTools(string toolId, IEnumerable<string> selectedToolIds)
    {
        var normalized = NormalizeSelection(selectedToolIds);
        return toolId == READ_WEB_PAGE_TOOL_ID && normalized.Contains(WEB_SEARCH_TOOL_ID);
    }

    public static ConfidenceLevel GetDefaultMinimumProviderConfidence(string toolId) => toolId switch
    {
        WEB_SEARCH_TOOL_ID => ConfidenceLevel.MEDIUM,
        READ_WEB_PAGE_TOOL_ID => ConfidenceLevel.MEDIUM,
        _ => ConfidenceLevel.NONE,
    };

    public static string GetMaxToolCallsLimitMessage() => $"Tool calling stopped because the maximum of {MAX_TOOL_CALLS} tool calls was reached.";

    public static string BuildToolPolicyPrompt(IEnumerable<ToolDefinition> definitions)
    {
        var policyLines = definitions
            .Select(x => x.PolicyInstructions?.Trim())
            .Where(x => !string.IsNullOrWhiteSpace(x))
            .Distinct(StringComparer.Ordinal)
            .ToList();
        if (policyLines.Count == 0)
            return string.Empty;

        return $"""
                Tool usage policy:
                {policyLines}
                """;
    }

    public static bool IsProviderConfidenceAllowed(ConfidenceLevel providerConfidence, ConfidenceLevel minimumToolConfidence) =>
        minimumToolConfidence is ConfidenceLevel.NONE || providerConfidence >= minimumToolConfidence;
}