1// SPDX-FileCopyrightText: Amolith <amolith@secluded.site>
 2//
 3// SPDX-License-Identifier: AGPL-3.0-or-later
 4
 5// Package timestamp provides an MCP tool for parsing natural language dates.
 6package timestamp
 7
 8import (
 9	"context"
10	"fmt"
11	"time"
12
13	"git.secluded.site/lune/internal/dateutil"
14	"github.com/modelcontextprotocol/go-sdk/mcp"
15)
16
17// ToolName is the name of this tool.
18const ToolName = "get_timestamp"
19
20// ToolDescription describes the tool for LLMs.
21const ToolDescription = `Parse natural language dates into RFC3339 timestamps.
22
23Use before passing dates to other tools. Supports PHP strtotime syntax:
24relative (+3 days, next Monday), named (March 5), ISO (2024-01-15).
25Empty input returns today.`
26
27// ToolAnnotations returns hints about tool behavior.
28func ToolAnnotations() *mcp.ToolAnnotations {
29	return &mcp.ToolAnnotations{
30		ReadOnlyHint: true,
31	}
32}
33
34// Input is the input schema for the timestamp tool.
35type Input struct {
36	Date string `json:"date" jsonschema:"Date/time expression to parse (empty = today)"`
37}
38
39// Output is the output schema for the timestamp tool.
40type Output struct {
41	Timestamp string `json:"timestamp"`
42	Date      string `json:"date"`
43}
44
45// Handler handles timestamp tool requests.
46type Handler struct {
47	timezone *time.Location
48}
49
50// NewHandler creates a new timestamp handler with the given timezone.
51func NewHandler(tz string) *Handler {
52	loc, err := time.LoadLocation(tz)
53	if err != nil {
54		loc = time.UTC
55	}
56
57	return &Handler{timezone: loc}
58}
59
60// Handle parses a natural language date and returns an RFC3339 timestamp.
61func (h *Handler) Handle(
62	_ context.Context,
63	_ *mcp.CallToolRequest,
64	input Input,
65) (*mcp.CallToolResult, Output, error) {
66	parsed, err := dateutil.ParseInTZ(input.Date, h.timezone)
67	if err != nil {
68		return &mcp.CallToolResult{
69			IsError: true,
70			Content: []mcp.Content{
71				&mcp.TextContent{Text: err.Error()},
72			},
73		}, Output{}, nil
74	}
75
76	t := parsed.In(h.timezone)
77	output := Output{
78		Timestamp: t.Format(time.RFC3339),
79		Date:      t.Format("2006-01-02"),
80	}
81
82	inputDisplay := input.Date
83	if inputDisplay == "" {
84		inputDisplay = "(empty)"
85	}
86
87	return &mcp.CallToolResult{
88		Content: []mcp.Content{&mcp.TextContent{
89			Text: fmt.Sprintf("Parsed %q → %s", inputDisplay, output.Timestamp),
90		}},
91	}, output, nil
92}