package main

import (
	"encoding/json"
	"os"
	"path/filepath"
	"testing"

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

func TestNewAgentKeepsItsIDAcrossOpens(t *testing.T) {
	dir := filepath.Join(t.TempDir(), "agent")
	agent, err := openAgent(dir)
	require.NoError(t, err)
	require.Len(t, agent.config.ID, 2*agentIDBytes)
	require.Equal(t, "gpt-6.1-sol", agent.config.Model)
	require.True(t, filepath.IsAbs(agent.config.Workdir))

	again, err := openAgent(dir)
	require.NoError(t, err)
	require.Equal(t, agent.config, again.config)

	info, err := os.Stat(dir)
	require.NoError(t, err)
	require.Equal(t, os.FileMode(0o700), info.Mode().Perm())
}

func TestNewAgentsGetDifferentIDs(t *testing.T) {
	first, err := openAgent(t.TempDir())
	require.NoError(t, err)

	second, err := openAgent(t.TempDir())
	require.NoError(t, err)
	require.Equal(t, first.config.Name, second.config.Name)
	require.NotEqual(t, first.CacheKey(), second.CacheKey())
}

func TestRenamedAgentKeepsItsCacheKey(t *testing.T) {
	dir := t.TempDir()
	agent, err := openAgent(dir)
	require.NoError(t, err)

	key := agent.CacheKey()
	require.Equal(t, "onechat-"+agent.config.ID, key)

	config := agent.config
	config.Name = "Lena"
	agentWriteTestConfig(t, dir, config)

	renamed, err := openAgent(dir)
	require.NoError(t, err)
	require.Equal(t, "Lena", renamed.config.Name)
	require.Equal(t, key, renamed.CacheKey())
}

func TestAgentConfigErrors(t *testing.T) {
	testCases := []struct {
		name   string
		config string
		err    string
	}{
		{
			name:   "unknown field",
			config: `{"id": "00112233445566778899aabbccddeeff", "nmae": "Lena"}`,
			err:    `unknown field "nmae"`,
		},
		{
			name:   "missing id",
			config: `{"name": "Lena"}`,
			err:    "id must be 32 hexadecimal digits",
		},
		{
			name:   "relative workdir",
			config: `{"id": "00112233445566778899aabbccddeeff", "workdir": "src"}`,
			err:    `workdir "src" is not an absolute path`,
		},
		{
			name:   "name of two lines",
			config: `{"id": "00112233445566778899aabbccddeeff", "name": "Le\nna"}`,
			err:    "name must be one line of text",
		},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			dir := t.TempDir()
			require.NoError(t, os.WriteFile(filepath.Join(dir, "config.json"), []byte(tc.config), 0o600))

			_, err := openAgent(dir)
			require.ErrorContains(t, err, tc.err)
		})
	}
}

func TestAgentPromptReadsTheInstructionsEachTime(t *testing.T) {
	dir := t.TempDir()
	agent, err := openAgent(dir)
	require.NoError(t, err)

	text, err := agent.Prompt()
	require.NoError(t, err)
	require.Equal(t, prompt(agent.config.Name, filepath.Join(dir, agentInstructionsFileName), ""), text)

	require.NoError(t, os.WriteFile(filepath.Join(dir, agentInstructionsFileName), []byte("I am Lena.\n"), 0o600))

	text, err = agent.Prompt()
	require.NoError(t, err)
	require.Equal(t, prompt(agent.config.Name, filepath.Join(dir, agentInstructionsFileName), "I am Lena."), text)
}

func TestAgentPromptUsesAnAbsoluteInstructionsPath(t *testing.T) {
	dir := t.TempDir()
	workdir, err := os.Getwd()
	require.NoError(t, err)

	relative, err := filepath.Rel(workdir, dir)
	require.NoError(t, err)
	require.False(t, filepath.IsAbs(relative))

	agent, err := openAgent(relative)
	require.NoError(t, err)

	text, err := agent.Prompt()
	require.NoError(t, err)
	require.Contains(t, text, "The user's instructions live in the file "+filepath.Join(dir, agentInstructionsFileName)+",")
}

// agentWriteTestConfig writes config as the config.json of the agent in dir.
func agentWriteTestConfig(t *testing.T, dir string, config AgentConfig) {
	t.Helper()

	data, err := json.Marshal(config)
	require.NoError(t, err)
	require.NoError(t, os.WriteFile(filepath.Join(dir, "config.json"), data, 0o600))
}