namespace ClaudeOverview.Models;

/// <summary>Whether the chat is mid-work or has handed the turn back to the human.</summary>
public enum ChatStatus
{
    Working,
    WaitingForUser,
    /// <summary>Claude is blocked on a tool-permission prompt, waiting for the human to approve.</summary>
    WaitingForPermission
}

/// <summary>
/// A single Claude Code chat (one transcript .jsonl file) plus its aggregated usage.
/// </summary>
public sealed class ClaudeSession
{
    public string SessionId { get; init; } = "";
    public string FilePath { get; init; } = "";

    /// <summary>Working directory the chat ran in (cwd from the transcript).</summary>
    public string Cwd { get; set; } = "";

    public string GitBranch { get; set; } = "";
    public string Model { get; set; } = "";
    public string Entrypoint { get; set; } = "";

    /// <summary>First human message, used as a fallback human-readable title.</summary>
    public string Title { get; set; } = "";

    /// <summary>
    /// The chat name VS Code generates and shows in its tab (an "ai-title" entry in the
    /// transcript). Empty until the extension has generated one for the chat.
    /// </summary>
    public string AiTitle { get; set; } = "";

    /// <summary>The name to show for the chat: the VS Code title when available, else the first prompt.</summary>
    public string DisplayTitle => AiTitle.Length > 0 ? AiTitle : Title;

    public DateTime LastActivityUtc { get; set; }

    /// <summary>
    /// Set by the scanner: true when the chat changed within the active window. Cold (false) chats
    /// are still listed, but rendered dimmed and without status colors.
    /// </summary>
    public bool IsActive { get; set; } = true;

    /// <summary>True for cold chats — listed for context but no longer actively running.</summary>
    public bool IsCold => !IsActive;

    // Aggregated token usage across all assistant messages in this chat.
    public long InputTokens { get; set; }
    public long OutputTokens { get; set; }
    public long CacheReadTokens { get; set; }
    public long CacheCreationTokens { get; set; }
    public int MessageCount { get; set; }

    public long TotalTokens => InputTokens + OutputTokens + CacheReadTokens + CacheCreationTokens;

    /// <summary>
    /// Tokens this chat consumed since the current session-limit window started (set by the scanner).
    /// Used to approximate each chat's slice of the session limit.
    /// </summary>
    public long SessionTokens { get; set; }

    /// <summary>This chat's share (0–100) of all tokens consumed across listed chats this window.</summary>
    public double SessionSharePercent { get; set; }

    public string SessionShareText => $"{SessionSharePercent:0}%";

    // ----- State of the last conversational turn (set by the scanner) -----

    /// <summary>Role of the last main-chain message ("assistant" or "user").</summary>
    public string LastRole { get; set; } = "";

    /// <summary>stop_reason of the last assistant message (e.g. "end_turn", "tool_use").</summary>
    public string LastStopReason { get; set; } = "";

    /// <summary>Tool names invoked by the last assistant message.</summary>
    public List<string> LastToolNames { get; set; } = new();

    /// <summary>Primary argument of each tool in <see cref="LastToolNames"/> (command / path / url), index-aligned.</summary>
    public List<string> LastToolArgs { get; set; } = new();

    /// <summary>
    /// Set by the scanner: true when every pending tool of the last assistant turn is auto-approved
    /// by the user's Claude Code permission settings. When so, a stale tool_use means a long-running
    /// approved tool, not a prompt — so we keep showing "working…" instead of "needs permission".
    /// </summary>
    public bool PendingToolsAutoApproved { get; set; }

    /// <summary>
    /// Set by the scanner: true when the last assistant tool_use has NOT yet been answered by a
    /// tool_result. Once a result arrives (even if Claude then thinks for a while before its next
    /// line), the tool clearly ran — so a quick command followed by long thinking is never mistaken
    /// for a permission prompt.
    /// </summary>
    public bool AwaitingToolResult { get; set; }

    /// <summary>Text of the last assistant message (used to detect a literal question).</summary>
    public string LastAssistantText { get; set; } = "";

    /// <summary>
    /// How long a pending tool_use must sit without a following tool_result before we treat it
    /// as a permission prompt (Claude blocked, waiting on the human) rather than a tool still
    /// running. Set once at startup from config. Kept small so the widget flags prompts quickly.
    /// </summary>
    public static int PendingToolStaleSeconds = 8;

    public ChatStatus Status
    {
        get
        {
            if (LastRole == "assistant")
            {
                // An interactive prompt tool means Claude is explicitly asking the user.
                if (LastToolNames.Contains("AskUserQuestion") || LastToolNames.Contains("ExitPlanMode"))
                    return ChatStatus.WaitingForUser;

                // Claude ended its turn and yielded back to the human.
                if (LastStopReason is "end_turn" or "stop_sequence")
                    return ChatStatus.WaitingForUser;

                // A trailing tool_use with no tool_result yet: the tool is either executing or
                // Claude Code is blocked on a permission prompt. The transcript can't tell these
                // apart directly, so we combine three signals: the tool_use is still unanswered
                // (a returned result means it ran — long post-tool thinking is NOT a prompt), it
                // isn't auto-approved by the user's permission settings (otherwise it'd just run),
                // AND the file has sat untouched past the stale threshold.
                if (AwaitingToolResult && LastToolNames.Count > 0 &&
                    !PendingToolsAutoApproved &&
                    DateTime.UtcNow - LastActivityUtc > TimeSpan.FromSeconds(PendingToolStaleSeconds))
                    return ChatStatus.WaitingForPermission;

                // tool_use (still fresh) / max_tokens etc. — still mid-work.
                return ChatStatus.Working;
            }

            // Last entry is a user/tool-result message: Claude is generating.
            return ChatStatus.Working;
        }
    }

    /// <summary>True whenever the chat needs the human — finished, asking, or awaiting permission.</summary>
    public bool IsWaiting => Status != ChatStatus.Working;

    /// <summary>True specifically when Claude is blocked on a tool-permission prompt.</summary>
    public bool NeedsPermission => Status == ChatStatus.WaitingForPermission;

    /// <summary>True when Claude is specifically posing a question (vs just finishing).</summary>
    public bool AsksQuestion =>
        IsWaiting &&
        (LastToolNames.Contains("AskUserQuestion") ||
         LastAssistantText.TrimEnd().EndsWith("?"));

    public string StatusText => Status switch
    {
        ChatStatus.WaitingForPermission => LastToolNames.Count > 0
            ? $"allow {LastToolNames[^1]}?"
            : "needs permission",
        ChatStatus.WaitingForUser => AsksQuestion ? "question for you" : "idle",
        _ => "working…"
    };

    // ----- Display helpers (bound directly in XAML) -----

    public string ProjectName
    {
        get
        {
            if (string.IsNullOrEmpty(Cwd)) return "(unknown)";
            var trimmed = Cwd.TrimEnd('/', '\\');
            var idx = trimmed.LastIndexOfAny(new[] { '/', '\\' });
            return idx >= 0 && idx < trimmed.Length - 1 ? trimmed[(idx + 1)..] : trimmed;
        }
    }

    public bool IsVsCode => Entrypoint == "claude-vscode";

    public string ModelShort => Model
        .Replace("claude-", "")
        .Replace("-20", " 20"); // cosmetic

    public string LastActivityLocal
    {
        get
        {
            var span = DateTime.UtcNow - LastActivityUtc;
            if (span < TimeSpan.FromSeconds(60)) return "just now";
            if (span < TimeSpan.FromMinutes(60)) return $"{(int)span.TotalMinutes}m ago";
            if (span < TimeSpan.FromHours(24)) return $"{(int)span.TotalHours}h ago";
            return LastActivityUtc.ToLocalTime().ToString("MMM d HH:mm");
        }
    }

    public string UsageSummary =>
        $"{Human(TotalTokens)} tok · {MessageCount} msg";

    public string UsageDetail =>
        $"in {Human(InputTokens)} · out {Human(OutputTokens)} · cache {Human(CacheReadTokens)}";

    private static string Human(long n) => n switch
    {
        >= 1_000_000 => $"{n / 1_000_000.0:0.0}M",
        >= 1_000 => $"{n / 1_000.0:0.0}k",
        _ => n.ToString()
    };
}