package conf_test

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

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

	"code.bcarlin.xyz/go/conf"
)

type testconf struct {
	inUpdate  func()
	String    string
	Invariant string
	Int       int
}

func (t testconf) Update() {
	if t.inUpdate != nil {
		t.inUpdate()
	}
}

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

	t.Run("with a valid file", func(t *testing.T) {
		t.Parallel()

		c := testconf{
			String:    "default string",
			Int:       1,
			Invariant: "should not change",
		}

		file := "test_data/valid.json"

		err := conf.LoadFile(file, &c)
		require.NoError(t, err)

		assert.Equal(t, "config string", c.String)
		assert.Equal(t, 42, c.Int)
		assert.Equal(t, "should not change", c.Invariant)
	})

	t.Run("with an invalid file", func(t *testing.T) {
		t.Parallel()

		c := testconf{
			String:    "default string",
			Int:       1,
			Invariant: "should not change",
		}

		file := "test_data/invalid.json"

		err := conf.LoadFile(file, &c)
		require.Error(t, err)

		assert.Equal(t, "default string", c.String)
		assert.Equal(t, 1, c.Int)
		assert.Equal(t, "should not change", c.Invariant)
	})

	t.Run("with a non existent file", func(t *testing.T) {
		t.Parallel()

		c := testconf{
			String:    "default string",
			Int:       1,
			Invariant: "should not change",
		}

		file := "does-not-exist.conf"

		err := conf.LoadFile(file, &c)
		require.Error(t, err)

		assert.Equal(t, "default string", c.String)
		assert.Equal(t, 1, c.Int)
		assert.Equal(t, "should not change", c.Invariant)
	})
}

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

	t.Run("with two valid files with different options", func(t *testing.T) {
		t.Parallel()

		c := testconf{}
		tmpDir := t.TempDir()

		content1 := []byte(`{"String": "foo"}`)
		content2 := []byte(`{"Int": 42}`)
		paths := []string{
			filepath.Join(tmpDir, "file1.json"),
			filepath.Join(tmpDir, "file2.json"),
		}

		err := os.WriteFile(paths[0], content1, 0o600)
		require.NoError(t, err)
		err = os.WriteFile(paths[1], content2, 0o600)
		require.NoError(t, err)

		err = conf.LoadFiles(&c, paths...)
		require.NoError(t, err)

		assert.Equal(t, "foo", c.String)
		assert.Equal(t, 42, c.Int)
	})

	t.Run("with two valid files with the same option", func(t *testing.T) {
		t.Parallel()

		c := testconf{}
		tmpDir := t.TempDir()

		content1 := []byte(`{"String": "foo"}`)
		content2 := []byte(`{"String": "bar"}`)
		paths := []string{
			filepath.Join(tmpDir, "file1.json"),
			filepath.Join(tmpDir, "file2.json"),
		}

		err := os.WriteFile(paths[0], content1, 0o600)
		require.NoError(t, err)
		err = os.WriteFile(paths[1], content2, 0o600)
		require.NoError(t, err)

		err = conf.LoadFiles(&c, paths...)
		require.NoError(t, err)

		assert.Equal(t, "bar", c.String)
	})

	t.Run("with one non-existing and one existing file", func(t *testing.T) {
		t.Parallel()

		c := testconf{}
		tmpDir := t.TempDir()

		content2 := []byte(`{"String": "bar"}`)
		paths := []string{
			"does-not-exist.json",
			filepath.Join(tmpDir, "file2.json"),
		}

		err := os.WriteFile(paths[1], content2, 0o600)
		require.NoError(t, err)

		err = conf.LoadFiles(&c, paths...)
		require.NoError(t, err)

		assert.Equal(t, "bar", c.String)
	})

	t.Run("with one valid and one invalid file", func(t *testing.T) {
		t.Parallel()

		c := testconf{}
		tmpDir := t.TempDir()

		content1 := []byte(`{"`)
		content2 := []byte(`{"String": "bar"}`)
		paths := []string{
			filepath.Join(tmpDir, "file1.json"),
			filepath.Join(tmpDir, "file2.json"),
		}

		err := os.WriteFile(paths[0], content1, 0o600)
		require.NoError(t, err)
		err = os.WriteFile(paths[1], content2, 0o600)
		require.NoError(t, err)

		err = conf.LoadFiles(&c, paths...)
		require.Error(t, err)

		assert.Equal(t, "", c.String)
	})
}

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

	t.Run("with a valid path", func(t *testing.T) {
		t.Parallel()

		c := testconf{
			String:    "default string",
			Invariant: "should not change",
			Int:       1,
		}
		tmpDir := t.TempDir()
		file := filepath.Join(tmpDir, "test.conf")

		err := conf.SaveFile(file, &c)
		require.NoError(t, err)

		assert.FileExists(t, file)

		expected := "{\n  \"String\": \"default string\",\n  \"Invariant\": \"should not change\",\n  \"Int\": 1\n}"
		got, err := os.ReadFile(file)
		require.NoError(t, err)
		assert.Equal(t, expected, string(got))
	})

	t.Run("with a valid path and invalid data", func(t *testing.T) {
		t.Parallel()

		tmpDir := t.TempDir()
		file := filepath.Join(tmpDir, "test.conf")

		err := conf.SaveFile(file, func() error { return nil })
		require.Error(t, err)

		assert.NoFileExists(t, file)
	})

	t.Run("with an invalid path", func(t *testing.T) {
		t.Parallel()

		c := testconf{
			String:    "default string",
			Invariant: "should not change",
			Int:       1,
		}
		file := "cannot/write/here.conf"

		err := conf.SaveFile(file, &c)
		require.Error(t, err)

		assert.NoFileExists(t, file)
	})
}

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

	t.Run("when the target file does not exist", func(t *testing.T) {
		t.Parallel()

		updated := false
		c := testconf{
			String:    "default string",
			Int:       1,
			Invariant: "should not change",
			inUpdate:  func() { updated = true },
		}
		tmpDir := t.TempDir()
		file := filepath.Join(tmpDir, "test.conf")

		err := conf.LoadAndUpdateFile(file, &c)
		require.NoError(t, err)

		var c2 testconf
		err = conf.LoadFile(file, &c2)
		require.NoError(t, err)
		assert.Equal(t, c.String, c2.String)
		assert.Equal(t, c.Int, c2.Int)
		assert.Equal(t, c.Invariant, c2.Invariant)

		assert.False(t, updated)
	})

	t.Run("when the path cannot be written", func(t *testing.T) {
		t.Parallel()

		updated := false
		c := testconf{
			String:    "default string",
			Int:       1,
			Invariant: "should not change",
			inUpdate:  func() { updated = true },
		}
		tmpDir := t.TempDir()
		file := filepath.Join(tmpDir, "does-not-exist", "test.conf")

		err := conf.LoadAndUpdateFile(file, &c)
		require.Error(t, err)

		assert.NoFileExists(t, file)

		assert.False(t, updated)
	})

	t.Run("when the config file is invalid", func(t *testing.T) {
		t.Parallel()

		updated := false
		c := testconf{
			String:    "default string",
			Int:       1,
			Invariant: "should not change",
			inUpdate:  func() { updated = true },
		}
		tmpDir := t.TempDir()
		file := filepath.Join(tmpDir, "test.conf")

		content := []byte(`String: not json`)
		err := os.WriteFile(file, content, 0o644)
		require.NoError(t, err)

		err = conf.LoadAndUpdateFile(file, &c)
		require.Error(t, err)

		assert.False(t, updated)
	})

	t.Run("when the config file is valid", func(t *testing.T) {
		t.Parallel()

		updated := false
		c := testconf{
			String:    "default string",
			Int:       1,
			Invariant: "should not change",
			inUpdate:  func() { updated = true },
		}
		tmpDir := t.TempDir()
		file := filepath.Join(tmpDir, "test.conf")

		content := []byte(`{"String": "config string", "Int": 42}`)
		err := os.WriteFile(file, content, 0o644)
		require.NoError(t, err)

		err = conf.LoadAndUpdateFile(file, &c)
		require.NoError(t, err)

		var c2 testconf
		err = conf.LoadFile(file, &c2)
		require.NoError(t, err)
		assert.Equal(t, "config string", c2.String)
		assert.Equal(t, 42, c2.Int)

		assert.True(t, updated)
	})

	t.Run("when the config file is missing options", func(t *testing.T) {
		t.Parallel()

		updated := false
		c := testconf{
			String:    "default string",
			Int:       1,
			Invariant: "should not change",
			inUpdate:  func() { updated = true },
		}
		tmpDir := t.TempDir()
		file := filepath.Join(tmpDir, "test.conf")

		content := []byte(`{"String": "config string"}`)
		err := os.WriteFile(file, content, 0o644)
		require.NoError(t, err)

		err = conf.LoadAndUpdateFile(file, &c)
		require.NoError(t, err)

		newContent, err := os.ReadFile(file)
		require.NoError(t, err)

		assert.Contains(t, string(newContent), "Int") //nolint:usestdlibvars // not the constant here
		assert.Contains(t, string(newContent), "Invariant")

		assert.True(t, updated)
	})

	t.Run("when the config contains unknown options", func(t *testing.T) {
		t.Parallel()

		updated := false
		c := testconf{
			String:    "default string",
			Int:       1,
			Invariant: "should not change",
			inUpdate:  func() { updated = true },
		}
		tmpDir := t.TempDir()
		file := filepath.Join(tmpDir, "test.conf")

		content := []byte(`{"String": "config string", "Foo": "blah"}`)
		err := os.WriteFile(file, content, 0o644)
		require.NoError(t, err)

		err = conf.LoadAndUpdateFile(file, &c)
		require.NoError(t, err)

		newContent, err := os.ReadFile(file)
		require.NoError(t, err)
		assert.NotContains(t, string(newContent), "Foo")

		assert.True(t, updated)
	})
}