package config

import (
	"encoding/json"
	"strings"
	"testing"
	"time"

	"gopkg.in/yaml.v3"
)

func TestDurationUnmarshalYAMLAccepted(t *testing.T) {
	tests := []struct {
		name string
		node string
		want time.Duration
	}{
		{"seconds", `5s`, 5 * time.Second},
		{"compound minutes seconds", `1m30s`, 90 * time.Second},
		{"milliseconds", `250ms`, 250 * time.Millisecond},
		{"hours minutes", `1h30m`, 90 * time.Minute},
		{"sub second", `1.5s`, 1500 * time.Millisecond},
		{"microseconds", `10us`, 10 * time.Microsecond},
		{"zero", `0s`, 0},
		{"negative", `-5s`, -5 * time.Second},
		{"padded", `"  30s  "`, 30 * time.Second},
		{"empty string is zero", `""`, 0},
		{"null is zero", `null`, 0},
		{"tilde is zero", `~`, 0},
		{"int seconds", `7`, 7 * time.Second},
		{"float seconds", `1.5`, 1500 * time.Millisecond},
		{"negative int seconds", `-7`, -7 * time.Second},
	}
	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			var got struct {
				D Duration `yaml:"d"`
			}
			if err := yaml.Unmarshal([]byte("d: "+tc.node), &got); err != nil {
				t.Fatalf("unmarshal %s: %v", tc.node, err)
			}
			if got.D.D() != tc.want {
				t.Errorf("d: %s = %v, want %v", tc.node, got.D.D(), tc.want)
			}
		})
	}
}

func TestDurationUnmarshalYAMLRejected(t *testing.T) {
	tests := []struct {
		name    string
		node    string
		mention string
	}{
		{"nonsense", `abc`, `"abc"`},
		{"nonsense", `abc`, `"abc"`},
		{"space before unit", `"5 s"`, `"5 s"`},
		{"unknown unit", `10x`, `"10x"`},
		{"overflow", `2562048h`, `"2562048h"`},
		{"float overflow", `1e400s`, `1e400s`},
		{"numeric seconds overflow", `1e30`, `"1e30"`},
	}
	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			var got struct {
				D Duration `yaml:"d"`
			}
			err := yaml.Unmarshal([]byte("d: "+tc.node), &got)
			if err == nil {
				t.Fatalf("unmarshal %s: expected error, got %v", tc.node, got.D.D())
			}
			if !strings.Contains(err.Error(), tc.mention) {
				t.Errorf("error %q does not mention offending value %s", err, tc.mention)
			}
		})
	}
}

func TestDurationUnmarshalYAMLNonScalar(t *testing.T) {
	for _, node := range []string{`{a: 1}`, `[1,2]`} {
		var got struct {
			D Duration `yaml:"d"`
		}
		if err := yaml.Unmarshal([]byte("d: "+node), &got); err == nil {
			t.Errorf("unmarshal d: %s: expected error, got %v", node, got.D.D())
		}
	}
}

func TestDurationMarshalYAMLRoundTrip(t *testing.T) {
	for _, d := range []Duration{
		Duration(5 * time.Second),
		Duration(90 * time.Second),
		Duration(250 * time.Millisecond),
		Duration(12 * time.Hour),
		Duration(0),
	} {
		out, err := yaml.Marshal(map[string]Duration{"d": d})
		if err != nil {
			t.Fatalf("marshal %v: %v", d.D(), err)
		}
		var back struct {
			D Duration `yaml:"d"`
		}
		if err := yaml.Unmarshal(out, &back); err != nil {
			t.Fatalf("unmarshal %q: %v", out, err)
		}
		if back.D != d {
			t.Errorf("round trip %v via %q: got %v", d.D(), strings.TrimSpace(string(out)), back.D.D())
		}
	}
}

// Duration has no custom JSON unmarshaller; pin what encoding/json does with
// it so a change here is a deliberate one.
func TestDurationJSONForm(t *testing.T) {
	var got struct {
		D Duration `json:"d"`
	}
	if err := json.Unmarshal([]byte(`{"d":5}`), &got); err != nil {
		t.Fatalf("bare number: %v", err)
	}
	if got.D.D() != 5*time.Nanosecond {
		t.Errorf("bare JSON number = %v (nanoseconds, not seconds)", got.D.D())
	}
	if err := json.Unmarshal([]byte(`{"d":"5s"}`), &got); err == nil {
		t.Errorf("quoted JSON duration decoded to %v; string form is unsupported", got.D.D())
	}
	out, err := json.Marshal(Duration(5 * time.Second))
	if err != nil {
		t.Fatalf("marshal: %v", err)
	}
	if string(out) != "5000000000" {
		t.Errorf("json.Marshal = %s, want nanoseconds", out)
	}
}

// clearEnv removes name for the rest of the test, restoring it afterwards.
func clearEnv(t *testing.T, name string) {
	t.Helper()
	if old, ok := os.LookupEnv(name); ok {
		t.Setenv(name, old) // registers the restore-on-cleanup
	}
	if err := os.Unsetenv(name); err != nil {
		t.Fatalf("unset %s: %v", name, err)
	}
}

func TestExpandEnvSubstitution(t *testing.T) {
	t.Setenv("FD_TEST_KEY", "s3cr3t")
	t.Setenv("FD_TEST_EMPTY", "")
	t.Setenv("FD_TEST_NESTED", "${FD_TEST_KEY}")
	clearEnv(t, "FD_TEST_MISSING")
	tests := []struct {
		name, in, want string
	}{
		{"double quoted scalar", `api_keys: ["${FD_TEST_KEY}"]` + "\n", `api_keys: ["s3cr3t"]` + "\n"},
		{"plain unquoted scalar", "cert_file: /etc/${FD_TEST_KEY}.pem\n", "cert_file: /etc/s3cr3t.pem\n"},
		{"single quoted scalar", "password: '${FD_TEST_KEY}'\n", "password: 's3cr3t'\n"},
		{"whole value", "password: ${FD_TEST_KEY}\n", "password: s3cr3t\n"},
		{"two references on one line", "x: ${FD_TEST_KEY}/${FD_TEST_KEY}\n", "x: s3cr3t/s3cr3t\n"},
		{"value is not rescanned", "x: ${FD_TEST_NESTED}\n", "x: ${FD_TEST_KEY}\n"},
		{"reference line comment", "# api_keys: ${FD_TEST_KEY}\n", "# api_keys: ${FD_TEST_KEY}\n"},
		{"reference trailing comment", "level: info # set ${FD_TEST_KEY} later\n", "level: info # set ${FD_TEST_KEY} later\n"},
		{"indented comment", "dns:\n  # port ${FD_TEST_KEY}\n  max_udp_size: 1232\n", "dns:\n  # port ${FD_TEST_KEY}\n  max_udp_size: 1232\n"},
		{"bare dollar in url", "url: https://x.invalid/?a=$b\n", "url: https://x.invalid/?a=$b\n"},
		{"bare dollar blocklist line", "      url: https://h.invalid/hosts?$format=raw$other\n", "      url: https://h.invalid/hosts?$format=raw$other\n"},
		{"bare dollar at end of line", "url: https://x.invalid/$\n", "url: https://x.invalid/$\n"},
		{"colon default when unset", "x: ${FD_TEST_MISSING:-fallback}\n", "x: fallback\n"},
		{"hyphen default when unset", "x: [${FD_TEST_MISSING-fallback}]\n", "x: [fallback]\n"},
		{"colon default when empty", "x: ${FD_TEST_EMPTY:-fallback}\n", "x: fallback\n"},
		{"hyphen default when empty stays empty", "x: [${FD_TEST_EMPTY-fallback}]\n", "x: []\n"},
		{"empty default", "x: [${FD_TEST_MISSING:-}]\n", "x: []\n"},
		{"empty value without default", "x: [${FD_TEST_EMPTY}]\n", "x: []\n"},
		{"hash without leading space is data", "x: a#${FD_TEST_KEY}\n", "x: a#s3cr3t\n"},
		{"hash inside double quotes is data", "x: \"# ${FD_TEST_KEY}\"\n", "x: \"# s3cr3t\"\n"},
		{"hash inside single quotes is data", "x: '# ${FD_TEST_KEY}'\n", "x: '# s3cr3t'\n"},
		{"crlf line ending", "x: ${FD_TEST_KEY}\r\ny: 1\r\n", "x: s3cr3t\r\ny: 1\r\n"},
		{"crlf comment", "# ${FD_TEST_KEY}\r\n", "# ${FD_TEST_KEY}\r\n"},
		{"no trailing newline", "x: ${FD_TEST_KEY}", "x: s3cr3t"},
	}
	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			got, err := expandEnv([]byte(tc.in))
			if err != nil {
				t.Fatalf("expandEnv(%q): %v", tc.in, err)
			}
			if string(got) != tc.want {
				t.Errorf("expandEnv(%q)\n got %q\nwant %q", tc.in, got, tc.want)
			}
		})
	}
}

func TestExpandEnvMultiLine(t *testing.T) {
	t.Setenv("FD_TEST_KEY", "abc123")
	clearEnv(t, "FD_TEST_MISSING")
	in := strings.Join([]string{
		"# leading comment ${FD_TEST_KEY}",
		"api:",
		"  auth:",
		`    api_keys: ["${FD_TEST_KEY}"] # trailing ${FD_TEST_KEY}`,
		"    username: ${FD_TEST_MISSING:-admin}",
		"    password: ${FD_TEST_MISSING-none}",
		"",
		"metrics:",
		"  enabled: false # ${FD_TEST_MISSING} in a comment is fine",
		"",
	}, "\n")
	want := strings.Join([]string{
		"# leading comment ${FD_TEST_KEY}",
		"api:",
		"  auth:",
		`    api_keys: ["abc123"] # trailing ${FD_TEST_KEY}`,
		"    username: admin",
		"    password: none",
		"",
		"metrics:",
		"  enabled: false # ${FD_TEST_MISSING} in a comment is fine",
		"",
	}, "\n")
	got, err := expandEnv([]byte(in))
	if err != nil {
		t.Fatalf("expandEnv: %v", err)
	}
	if string(got) != want {
		t.Errorf("expandEnv multi-line\n got %q\nwant %q", got, want)
	}
}

func TestExpandEnvWithoutReferencesIsByteIdentical(t *testing.T) {
	raw := []byte("# no references here\nurl: https://x.invalid/?a=$b&c=${not_this}\n'# ${FD_TEST_KEY}'\n")
	clearEnv(t, "FD_TEST_KEY")
	got, err := expandEnv(raw)
	if err != nil {
		t.Fatalf("expandEnv: %v", err)
	}
	if !bytes.Equal(got, raw) {
		t.Errorf("expandEnv changed a document with no references:\n got %q\nwant %q", got, raw)
	}
}

func TestExpandEnvErrors(t *testing.T) {
	clearEnv(t, "FD_TEST_MISSING")
	t.Setenv("FD_TEST_KEY", "abc123")
	tests := []struct {
		name, in string
		mentions []string
	}{
		{"unset without default", "x: ${FD_TEST_MISSING}\n", []string{"FD_TEST_MISSING", "line 1:"}},
		{"unset on third line", "a: 1\nb: 2\nc: ${FD_TEST_MISSING}\n", []string{"FD_TEST_MISSING", "line 3:"}},
		{"empty-but-set without default", "x: [${FD_TEST_MISSING}]\n", []string{"FD_TEST_MISSING"}},
		{"unterminated reference", "x: ${FD_TEST_KEY\n", []string{"unterminated ${"}},
		{"unterminated on later line", "a: 1\nb: ${FD_TEST_KEY\n", []string{"unterminated ${", "line 2:"}},
		{"empty name", "x: ${}\n", []string{"empty variable name in ${}"}},
		{"empty name with colon default", "x: ${:-fallback}\n", []string{"empty variable name"}},
		{"unterminated inside comment is ignored", "# x: ${FD_TEST_KEY\ny: 1\n", nil},
	}
	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			got, err := expandEnv([]byte(tc.in))
			if len(tc.mentions) == 0 {
				if err != nil {
					t.Fatalf("expandEnv(%q) = %v, want success", tc.in, err)
				}
				if string(got) != tc.in {
					t.Errorf("expandEnv(%q) = %q, want it copied verbatim", tc.in, got)
				}
				return
			}
			if err == nil {
				t.Fatalf("expandEnv(%q) = %q, want error", tc.in, got)
			}
			for _, m := range tc.mentions {
				if !strings.Contains(err.Error(), m) {
					t.Errorf("error %q does not mention %q", err, m)
				}
			}
		})
	}
}

func TestLoadSubstitutesEnvInFile(t *testing.T) {
	t.Setenv("FD_TEST_KEY", "long-random-api-key")
	t.Setenv("FD_TEST_PW", "p@ss")
	path := writeTempConfig(t, `api:
  auth:
    mode: apikey
    api_keys: ["${FD_TEST_KEY}"]
    username: 'admin-${FD_TEST_PW}'
    password: prefix-${FD_TEST_PW}
    # the key is documented here: ${FD_TEST_KEY}
`)
	cfg, err := Load(path)
	if err != nil {
		t.Fatalf("Load: %v", err)
	}
	want := []string{"long-random-api-key"}
	if len(cfg.API.Auth.APIKeys) != 1 || cfg.API.Auth.APIKeys[0] != want[0] {
		t.Errorf("api_keys = %q, want %q", cfg.API.Auth.APIKeys, want)
	}
	if cfg.API.Auth.Username != "admin-p@ss" {
		t.Errorf("username = %q, want admin-p@ss", cfg.API.Auth.Username)
	}
	if cfg.API.Auth.Password != "prefix-p@ss" {
		t.Errorf("password = %q, want prefix-p@ss", cfg.API.Auth.Password)
	}
}

func TestLoadUnsetEnvIsFatalAndNamesVariable(t *testing.T) {
	clearEnv(t, "FD_TEST_MISSING")
	path := writeTempConfig(t, "api:\n  auth:\n    mode: apikey\n    api_keys: [\"${FD_TEST_MISSING}\"]\n")
	_, err := Load(path)
	if err == nil {
		t.Fatal("Load: want error for unset variable")
	}
	for _, want := range []string{"FD_TEST_MISSING", path} {
		if !strings.Contains(err.Error(), want) {
			t.Errorf("error %q does not mention %q", err, want)
		}
	}
}

func writeTempConfig(t *testing.T, content string) string {
	t.Helper()
	path := filepath.Join(t.TempDir(), "config.yaml")
	if err := os.WriteFile(path, []byte(content), 0o600); err != nil {
		t.Fatalf("write config: %v", err)
	}
	return path
}