package config

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

const validTOML = `
[server]
listen_addr = ":8443"
tls_cert = "/srv/mcr/certs/cert.pem"
tls_key = "/srv/mcr/certs/key.pem"

[database]
path = "/srv/mcr/mcr.db"

[storage]
layers_path = "/srv/mcr/layers"
uploads_path = "/srv/mcr/uploads"

[mcias]
server_url = "https://mcias.metacircular.net:8443"
service_name = "mcr"
tags = ["env:restricted"]

[log]
level = "debug"
`

func writeConfig(t *testing.T, content string) string {
	t.Helper()
	dir := t.TempDir()
	path := filepath.Join(dir, "mcr.toml")
	if err := os.WriteFile(path, []byte(content), 0600); err != nil {
		t.Fatalf("write config: %v", err)
	}
	return path
}

func TestLoadValidConfig(t *testing.T) {
	path := writeConfig(t, validTOML)
	cfg, err := Load(path)
	if err != nil {
		t.Fatalf("Load: %v", err)
	}

	if cfg.Server.ListenAddr != ":8443" {
		t.Fatalf("listen_addr: got %q, want %q", cfg.Server.ListenAddr, ":8443")
	}
	if cfg.MCIAS.ServiceName != "mcr" {
		t.Fatalf("service_name: got %q, want %q", cfg.MCIAS.ServiceName, "mcr")
	}
	if len(cfg.MCIAS.Tags) != 1 || cfg.MCIAS.Tags[0] != "env:restricted" {
		t.Fatalf("tags: got %v, want [env:restricted]", cfg.MCIAS.Tags)
	}
	if cfg.Log.Level != "debug" {
		t.Fatalf("log.level: got %q, want %q", cfg.Log.Level, "debug")
	}
}

func TestLoadDefaults(t *testing.T) {
	path := writeConfig(t, validTOML)
	cfg, err := Load(path)
	if err != nil {
		t.Fatalf("Load: %v", err)
	}

	if cfg.Server.ReadTimeout.Seconds() != 30 {
		t.Fatalf("read_timeout: got %v, want 30s", cfg.Server.ReadTimeout)
	}
	if cfg.Server.WriteTimeout != 0 {
		t.Fatalf("write_timeout: got %v, want 0", cfg.Server.WriteTimeout)
	}
	if cfg.Server.IdleTimeout.Seconds() != 120 {
		t.Fatalf("idle_timeout: got %v, want 120s", cfg.Server.IdleTimeout)
	}
	if cfg.Server.ShutdownTimeout.Seconds() != 60 {
		t.Fatalf("shutdown_timeout: got %v, want 60s", cfg.Server.ShutdownTimeout)
	}
}

func TestLoadUploadsPathDefault(t *testing.T) {
	toml := `
[server]
listen_addr = ":8443"
tls_cert = "/srv/mcr/certs/cert.pem"
tls_key = "/srv/mcr/certs/key.pem"

[database]
path = "/srv/mcr/mcr.db"

[storage]
layers_path = "/srv/mcr/layers"

[mcias]
server_url = "https://mcias.metacircular.net:8443"
`
	path := writeConfig(t, toml)
	cfg, err := Load(path)
	if err != nil {
		t.Fatalf("Load: %v", err)
	}

	want := filepath.Join(filepath.Dir("/srv/mcr/layers"), "uploads")
	if cfg.Storage.UploadsPath != want {
		t.Fatalf("uploads_path: got %q, want %q", cfg.Storage.UploadsPath, want)
	}
}

func TestLoadMissingRequiredFields(t *testing.T) {
	tests := []struct {
		name string
		toml string
		want string
	}{
		{
			name: "missing listen_addr",
			toml: `
[server]
tls_cert = "/c"
tls_key = "/k"
[database]
path = "/d"
[storage]
layers_path = "/l"
[mcias]
server_url = "https://m"
`,
			want: "server.listen_addr",
		},
		{
			name: "missing tls_cert",
			toml: `
[server]
listen_addr = ":8443"
tls_key = "/k"
[database]
path = "/d"
[storage]
layers_path = "/l"
[mcias]
server_url = "https://m"
`,
			want: "server.tls_cert",
		},
		{
			name: "missing database.path",
			toml: `
[server]
listen_addr = ":8443"
tls_cert = "/c"
tls_key = "/k"
[storage]
layers_path = "/l"
[mcias]
server_url = "https://m"
`,
			want: "database.path",
		},
		{
			name: "missing storage.layers_path",
			toml: `
[server]
listen_addr = ":8443"
tls_cert = "/c"
tls_key = "/k"
[database]
path = "/d"
[mcias]
server_url = "https://m"
`,
			want: "storage.layers_path",
		},
		{
			name: "missing mcias.server_url",
			toml: `
[server]
listen_addr = ":8443"
tls_cert = "/c"
tls_key = "/k"
[database]
path = "/d"
[storage]
layers_path = "/l"
`,
			want: "mcias.server_url",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			path := writeConfig(t, tt.toml)
			_, err := Load(path)
			if err == nil {
				t.Fatal("expected error, got nil")
			}
			if got := err.Error(); !contains(got, tt.want) {
				t.Fatalf("error %q does not mention %q", got, tt.want)
			}
		})
	}
}

func TestEnvOverride(t *testing.T) {
	path := writeConfig(t, validTOML)

	t.Setenv("MCR_SERVER_LISTEN_ADDR", ":9999")
	t.Setenv("MCR_LOG_LEVEL", "warn")

	cfg, err := Load(path)
	if err != nil {
		t.Fatalf("Load: %v", err)
	}

	if cfg.Server.ListenAddr != ":9999" {
		t.Fatalf("listen_addr: got %q, want %q", cfg.Server.ListenAddr, ":9999")
	}
	if cfg.Log.Level != "warn" {
		t.Fatalf("log.level: got %q, want %q", cfg.Log.Level, "warn")
	}
}

func TestEnvOverrideDuration(t *testing.T) {
	path := writeConfig(t, validTOML)

	t.Setenv("MCR_SERVER_READ_TIMEOUT", "5s")

	cfg, err := Load(path)
	if err != nil {
		t.Fatalf("Load: %v", err)
	}

	if cfg.Server.ReadTimeout.Seconds() != 5 {
		t.Fatalf("read_timeout: got %v, want 5s", cfg.Server.ReadTimeout)
	}
}

func TestSameFilesystemCheck(t *testing.T) {
	dir := t.TempDir()
	layersPath := filepath.Join(dir, "layers")
	uploadsPath := filepath.Join(dir, "uploads")

	// Both under the same tmpdir → same filesystem.
	toml := `
[server]
listen_addr = ":8443"
tls_cert = "/srv/mcr/certs/cert.pem"
tls_key = "/srv/mcr/certs/key.pem"

[database]
path = "/srv/mcr/mcr.db"

[storage]
layers_path = "` + layersPath + `"
uploads_path = "` + uploadsPath + `"

[mcias]
server_url = "https://mcias.metacircular.net:8443"
`
	path := writeConfig(t, toml)
	_, err := Load(path)
	if err != nil {
		t.Fatalf("expected same-filesystem check to pass: %v", err)
	}
}

func contains(s, substr string) bool {
	return len(s) >= len(substr) && searchString(s, substr)
}

func searchString(s, substr string) bool {
	for i := 0; i <= len(s)-len(substr); i++ {
		if s[i:i+len(substr)] == substr {
			return true
		}
	}
	return false
}