package settings

import (
	"bytes"
	"errors"
	"fmt"
	"log"
	"maps"
	"os"
	"strings"
	"testing"
	"time"
)

const (
	TheTestFilename = "settings_test.settings"
)

var (
	AdditionalKeyValuePairs = map[string]string{
		"D": "d",
		"E": "e",
		"F": "f",
	}
)

func TestSettings(t *testing.T) {
	err := os.Remove(TheTestFilename)
	if err != nil && !errors.Is(err, os.ErrNotExist) {
		t.Fatalf("error cleaning up %s from previous run: %v\n", TheTestFilename, err)
	}
	var buffer bytes.Buffer
	err = WriteMapToWriter(&buffer, KeyValuePairs)
	if err != nil {
		t.Fatalf("error writing test data to *bytes.Buffer: %v\n", err)
	}
	err = os.WriteFile(TheTestFilename, buffer.Bytes(), 0664)
	if err != nil {
		t.Fatalf("error writing %s: %v\n", TheTestFilename, err)
	}
	defer func() {
		if err := os.Remove(TheTestFilename); err != nil {
			t.Fatalf("error cleaning up %s from this run: %v\n", TheTestFilename, err)
		}
	}()
	settings := NewSettingsWithContext(t.Context(), TheTestFilename, false)
	if want, got := TheTestFilename, settings.GetFilename(); want != got {
		t.Fatalf("error: wanted '%s'; got '%s'\n", want, got)
	} else if got := settings.modtime; got.Equal(time.Time{}) {
		t.Fatalf("error: modtime == (time.Time{}) - not updated when initialized")
	} else {
		for k, v := range KeyValuePairs {
			if !settings.ContainsKey(k) {
				t.Fatalf("error: key '%s' not found\n", k)
			} else if want, got := v, settings.GetKeyValue(k); want != got {
				t.Fatalf("error: wanted '%s' for key '%s'; got '%s'\n", want, k, got)
			}
		}
	}
	// change the filename
	TheNewTestFilename := fmt.Sprintf("New%s", TheTestFilename)
	buffer.Reset()
	err = WriteMapToWriter(&buffer, AdditionalKeyValuePairs)
	if err != nil {
		t.Fatalf("error writing new map to *bytes.Buffer: %v\n", err)
	}
	err = os.WriteFile(TheNewTestFilename, buffer.Bytes(), 0664)
	if err != nil {
		t.Fatalf("error writing new test file %s: %v\n", TheNewTestFilename, err)
	}
	defer func() {
		if err := os.Remove(TheNewTestFilename); err != nil {
			t.Fatalf("error deleting %s: %v", TheNewTestFilename, err)
		}
	}()
	if updated := settings.SetFilename(TheNewTestFilename); !updated {
		t.Fatalf("error: SetFilename() indicated the filename was not updated...\n")
	} else if updated := settings.SetFilename(settings.GetFilename()); updated {
		t.Fatalf("error: setting filename to itself still resulted in updated=true\n")
	}
	for k, v := range AdditionalKeyValuePairs {
		if !settings.ContainsKey(k) {
			t.Fatalf("error: key '%s' not found\n", k)
		} else if want, got := v, settings.GetKeyValue(k); want != got {
			t.Fatalf("error: wanted '%s' for key '%s'; got '%s'\n", want, k, got)
		}
	}
	// update the file, wait, then try again
	newKeyValuePairs := make(map[string]string)
	maps.Copy(newKeyValuePairs, KeyValuePairs)
	maps.Copy(newKeyValuePairs, AdditionalKeyValuePairs)
	newKeyValuePairs["G"] = "g"
	buffer.Reset()
	err = WriteMapToWriter(&buffer, newKeyValuePairs)
	if err != nil {
		t.Fatalf("error writing new key value pairs to *bytes.Buffer: %v\n", err)
	}
	err = os.WriteFile(TheNewTestFilename, buffer.Bytes(), 0664)
	if err != nil {
		t.Fatalf("error writing updates to %s: %v\n", TheNewTestFilename, err)
	}
	select {
	case <-t.Context().Done():
		t.Fatalf("error: timed out before finishing wait")
	case <-time.After(time.Duration(float64(MaintenanceRoutinePace.Nanoseconds()) * 1.1)):
	}
	for k, v := range newKeyValuePairs {
		if !settings.ContainsKey(k) {
			t.Fatalf("error: key '%s' not found in settings\n", k)
		} else if want, got := v, settings.GetKeyValue(k); want != got {
			t.Fatalf("error: wanted '%s' for key '%s'; got '%s'\n", want, k, got)
		}
	}
	buffer.Reset()
	defaultLogWriter := log.Writer()
	log.SetOutput(&buffer)
	// set settings to a fake filename
	WarnIfFileNotFound = true
	if updated := settings.SetFilename("fakefilename.txt"); !updated {
		t.Fatalf("failed to update filename to fake filename...\n")
	}
	log.SetOutput(defaultLogWriter)
	WarnIfFileNotFound = false
	if !strings.Contains(buffer.String(), "no such file or directory") {
		t.Fatalf("error: wanted error indicating 'no such file or directory'; got %v\n", err)
	}
}