package config

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

// writeUserConfig points XDG_CONFIG_HOME at a temporary directory and puts a
// config file in it, so tests never touch the real one.
func writeUserConfig(t *testing.T, body string) string {
	t.Helper()
	dir := t.TempDir()
	t.Setenv("XDG_CONFIG_HOME", dir)
	if body == "" {
		return dir
	}
	cfgDir := filepath.Join(dir, "money")
	if err := os.MkdirAll(cfgDir, 0o755); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(cfgDir, "config.toml"), []byte(body), 0o644); err != nil {
		t.Fatal(err)
	}
	return dir
}

func TestResolveRootPrecedence(t *testing.T) {
	home, err := os.UserHomeDir()
	if err != nil {
		t.Skip("no home directory in this environment")
	}

	t.Run("flag beats everything", func(t *testing.T) {
		writeUserConfig(t, "root = \"/from/config\"\n")
		t.Setenv("MONEY_ROOT", "/from/env")

		root, source, err := ResolveRoot("/from/flag")
		if err != nil {
			t.Fatal(err)
		}
		if root != "/from/flag" || source != RootFromFlag {
			t.Errorf("got %q from %q, want /from/flag from the flag", root, source)
		}
	})

	t.Run("env beats config", func(t *testing.T) {
		writeUserConfig(t, "root = \"/from/config\"\n")
		t.Setenv("MONEY_ROOT", "/from/env")

		root, source, err := ResolveRoot("")
		if err != nil {
			t.Fatal(err)
		}
		if root != "/from/env" || source != RootFromEnv {
			t.Errorf("got %q from %q, want /from/env from the environment", root, source)
		}
	})

	t.Run("config beats the default", func(t *testing.T) {
		writeUserConfig(t, "root = \"/from/config\"\n")
		t.Setenv("MONEY_ROOT", "")

		root, source, err := ResolveRoot("")
		if err != nil {
			t.Fatal(err)
		}
		if root != "/from/config" || source != RootFromConfig {
			t.Errorf("got %q from %q, want /from/config from the config file", root, source)
		}
	})

	t.Run("default when nothing is set", func(t *testing.T) {
		writeUserConfig(t, "") // XDG dir exists but holds no config file
		t.Setenv("MONEY_ROOT", "")

		root, source, err := ResolveRoot("")
		if err != nil {
			t.Fatal(err)
		}
		want := filepath.Join(home, "money")
		if root != want || source != RootFromDefault {
			t.Errorf("got %q from %q, want %q from the default", root, source, want)
		}
	})

	// A hand-written config file is likely to contain a tilde, which no shell
	// has expanded for us.
	t.Run("tilde in the config file is expanded", func(t *testing.T) {
		writeUserConfig(t, "root = \"~/finances\"\n")
		t.Setenv("MONEY_ROOT", "")

		root, _, err := ResolveRoot("")
		if err != nil {
			t.Fatal(err)
		}
		want := filepath.Join(home, "finances")
		if root != want {
			t.Errorf("root = %q, want %q", root, want)
		}
	})

	t.Run("relative paths become absolute", func(t *testing.T) {
		writeUserConfig(t, "")
		t.Setenv("MONEY_ROOT", "some/relative/dir")

		root, _, err := ResolveRoot("")
		if err != nil {
			t.Fatal(err)
		}
		if !filepath.IsAbs(root) {
			t.Errorf("root = %q, want an absolute path", root)
		}
	})
}

func TestUserConfigPathFollowsXDG(t *testing.T) {
	t.Setenv("XDG_CONFIG_HOME", "/custom/config")
	path, err := UserConfigPath()
	if err != nil {
		t.Fatal(err)
	}
	if want := "/custom/config/money/config.toml"; path != want {
		t.Errorf("path = %q, want %q", path, want)
	}

	// Unset, it falls back to ~/.config.
	t.Setenv("XDG_CONFIG_HOME", "")
	home, err := os.UserHomeDir()
	if err != nil {
		t.Skip("no home directory in this environment")
	}
	path, err = UserConfigPath()
	if err != nil {
		t.Fatal(err)
	}
	if want := filepath.Join(home, ".config", "money", "config.toml"); path != want {
		t.Errorf("path = %q, want %q", path, want)
	}
}

// A missing config file is normal, not an error.
func TestLoadUserConfigMissingFile(t *testing.T) {
	writeUserConfig(t, "")
	c, path, err := LoadUserConfig()
	if err != nil {
		t.Fatalf("a missing config file should not be an error: %v", err)
	}
	if c.Root != "" {
		t.Errorf("root = %q, want empty", c.Root)
	}
	if path == "" {
		t.Error("expected the path to be reported even when the file is absent")
	}
}

// A malformed config file is an error, so a typo does not silently send the
// tool to the wrong directory.
func TestLoadUserConfigMalformed(t *testing.T) {
	writeUserConfig(t, "root = this is not valid toml\n")
	if _, _, err := LoadUserConfig(); err == nil {
		t.Error("expected an error for a malformed config file")
	}
}