package cmd

import (
	"os"
	"strings"
	"testing"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

func TestBuildChangelogMessages(t *testing.T) {
	t.Parallel()

	log := `feat: add changelog command

Implements #1
---
fix: typo in docs
---`
	version := "v0.2.0"

	messages := buildChangelogMessages(log, version)

	require.Len(t, messages, 2)
	assert.Equal(t, "system", messages[0]["role"])
	assert.Contains(t, messages[0]["content"], "Generate a changelog section")
	assert.Contains(t, messages[0]["content"], "### Added")
	assert.Contains(t, messages[0]["content"], "### Changed")
	assert.Contains(t, messages[0]["content"], "### Fixed")
	assert.Equal(t, "user", messages[1]["role"])
	assert.Contains(t, messages[1]["content"], "Version: v0.2.0")
	assert.Contains(t, messages[1]["content"], log)
}

func TestBuildFullChangelog(t *testing.T) {
	t.Parallel()

	newSection := "## [v0.2.0] - 2026-03-03\n\n### Added\n- changelog command\n"

	t.Run("creates new file with header", func(t *testing.T) {
		t.Parallel()
		// nolint:tparallel // os.Chdir affects the entire process
		tmpDir := t.TempDir()

		originalWd, err := os.Getwd()
		require.NoError(t, err)
		t.Cleanup(func() {
			require.NoError(t, os.Chdir(originalWd))
		})
		require.NoError(t, os.Chdir(tmpDir))

		result := buildFullChangelog(newSection)

		assert.Contains(t, result, "# Changelog")
		assert.Contains(t, result, "All notable changes to this project will be documented in this file.")
		assert.Contains(t, result, newSection)
	})

	t.Run("prepends to existing file", func(t *testing.T) {
		t.Parallel()
		// nolint:tparallel // os.Chdir affects the entire process
		tmpDir := t.TempDir()

		originalWd, err := os.Getwd()
		require.NoError(t, err)
		t.Cleanup(func() {
			require.NoError(t, os.Chdir(originalWd))
		})
		require.NoError(t, os.Chdir(tmpDir))

		// Simulate existing changelog
		existing := `# Changelog

All notable changes to this project will be documented in this file.

## [v0.1.0] - 2025-01-01

### Fixed
- old bug
`
		require.NoError(t, os.WriteFile("CHANGELOG.md", []byte(existing), 0600))

		result := buildFullChangelog(newSection)

		assert.True(t, strings.HasPrefix(result, newSection), "new version section must be prepended at the top")
		assert.Contains(t, result, "old bug")
	})
}

func TestChangelogCmd_Flags(t *testing.T) {
	t.Parallel()

	require.NotNil(t, changelogCmd)

	stdoutFlag := changelogCmd.Flags().Lookup("stdout")
	require.NotNil(t, stdoutFlag)
	assert.Equal(t, "Print ONLY the new section (ideal for Gitea release notes)", stdoutFlag.Usage)

	versionFlag := changelogCmd.Flags().Lookup("version")
	require.NotNil(t, versionFlag)
	assert.Equal(t, "V", versionFlag.Shorthand)

	commitFlag := changelogCmd.Flags().Lookup("commit")
	require.NotNil(t, commitFlag)
	assert.Equal(t, "After writing, remind to run grokkit commit", commitFlag.Usage)

	sinceFlag := changelogCmd.Flags().Lookup("since")
	require.NotNil(t, sinceFlag)
}