package main

import (
	"fmt"
	"os"
	"path/filepath"
	"testing"

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

func TestMemoryRestartLoadsTheSameView(t *testing.T) {
	root := t.TempDir()
	clock := newTestClock()
	memory, err := openMemory(t.Context(), root, clock.Now)
	require.NoError(t, err)

	memory.chat.high = 200
	memory.chat.low = 100
	for n := range 100 {
		_, err = memory.Append("user", fmt.Sprint(n))
		require.NoError(t, err)
	}

	view := memory.View()
	saved, err := os.ReadFile(filepath.Join(root, "view.json"))
	require.NoError(t, err)
	require.Less(t, len(memory.chat.lines), 100)
	require.NoError(t, memory.Close())

	memory, err = openMemory(t.Context(), root, clock.Now)
	require.NoError(t, err)

	defer func() {
		require.NoError(t, memory.Close())
	}()

	require.Equal(t, view, memory.View())

	loaded, err := os.ReadFile(filepath.Join(root, "view.json"))
	require.NoError(t, err)
	require.Equal(t, saved, loaded)
}

func TestMemoryBuildsFreeParents(t *testing.T) {
	memory, err := openMemory(t.Context(), t.TempDir(), newTestClock().Now)
	require.NoError(t, err)

	defer func() {
		require.NoError(t, memory.Close())
	}()

	for _, text := range []string{"a", "b", "c", "d"} {
		_, err = memory.Append("user", text)
		require.NoError(t, err)
	}

	node, built := memory.tree.Node(2, 0)
	require.True(t, built)
	require.Equal(t, "user: a\nuser: b\nuser: c\nuser: d", node.Text)
}

func TestMemoryKeepsALongMessageOutOfTheView(t *testing.T) {
	memory, err := openMemory(t.Context(), t.TempDir(), newTestClock().Now)
	require.NoError(t, err)

	defer func() {
		require.NoError(t, memory.Close())
	}()

	_, err = memory.Append("echo", string(make([]byte, nodeBytes)))
	require.NoError(t, err)

	require.Equal(t, "<chat>\n0+1|"+pending+"\n</chat>", memory.View())
}

func TestMemoryCoversMessagesAfterTheSavedView(t *testing.T) {
	root := t.TempDir()
	clock := newTestClock()
	memory, err := openMemory(t.Context(), root, clock.Now)
	require.NoError(t, err)

	_, err = memory.Append("user", "a")
	require.NoError(t, err)

	_, err = memory.log.Append("reply", "b")
	require.NoError(t, err)
	require.NoError(t, memory.Close())

	memory, err = openMemory(t.Context(), root, clock.Now)
	require.NoError(t, err)

	defer func() {
		require.NoError(t, memory.Close())
	}()

	require.Equal(t, "<chat>\n0+1|user: a\n1+1|reply: b\n</chat>", memory.View())
}

func TestMemoryRefusesToRebuildAMissingView(t *testing.T) {
	root := t.TempDir()
	clock := newTestClock()
	memory, err := openMemory(t.Context(), root, clock.Now)
	require.NoError(t, err)

	_, err = memory.Append("user", "a")
	require.NoError(t, err)
	require.NoError(t, memory.Close())
	require.NoError(t, os.Remove(filepath.Join(root, "view.json")))

	_, err = openMemory(t.Context(), root, clock.Now)
	require.ErrorIs(t, err, errNoView)
}