package majordomo

import (
	"context"
	"errors"
	"slices"
	"strings"
	"testing"

	"gitea.stevedudenhoeffer.com/steve/majordomo/provider/fake"
)

// newTestRegistry returns a registry isolated from the process environment.
func newTestRegistry(t *testing.T, opts ...RegistryOption) *Registry {
	t.Helper()
	opts = append([]RegistryOption{
		WithoutEnvProviders(),
		WithEnvLookup(func(string) string { return "" }),
	}, opts...)
	return New(opts...)
}

// targetsOf extracts the resolved chain keys from a parsed model.
func targetsOf(t *testing.T, m Model) []string {
	t.Helper()
	c, ok := m.(*chain)
	if !ok {
		t.Fatalf("Parse returned %T, want *chain", m)
	}
	return c.Targets()
}

func TestParseSingleTarget(t *testing.T) {
	r := newTestRegistry(t)
	r.RegisterProvider(fake.New("fp"))

	m, err := r.Parse("fp/some-model:7b")
	if err != nil {
		t.Fatalf("Parse: %v", err)
	}
	want := []string{"fp/some-model:7b"}
	if got := targetsOf(t, m); !slices.Equal(got, want) {
		t.Errorf("targets = %v, want %v", got, want)
	}

	resp, err := m.Generate(context.Background(), Request{Messages: []Message{UserText("hi")}})
	if err != nil {
		t.Fatalf("Generate: %v", err)
	}
	if resp.Text() == "" {
		t.Error("empty response text")
	}
	if resp.Model != "fp/some-model:7b" {
		t.Errorf("resp.Model = %q, want fp/some-model:7b", resp.Model)
	}
}

func TestParseModelIDIsVerbatim(t *testing.T) {
	r := newTestRegistry(t)
	r.RegisterProvider(fake.New("google"))
	r.RegisterProvider(fake.New("ollama-cloud"))

	// Everything after the first slash, up to the next comma, is the model
	// id: colons and additional slashes pass through untouched.
	for spec, want := range map[string]string{
		"ollama-cloud/minimax-m3:cloud":       "ollama-cloud/minimax-m3:cloud",
		"google/models/gemini-3.0-pro":        "google/models/gemini-3.0-pro",
		"ollama-cloud/qwen3-coder:480b-cloud": "ollama-cloud/qwen3-coder:480b-cloud",
	} {
		m, err := r.Parse(spec)
		if err != nil {
			t.Fatalf("Parse(%q): %v", spec, err)
		}
		if got := targetsOf(t, m); !slices.Equal(got, []string{want}) {
			t.Errorf("Parse(%q) targets = %v, want [%s]", spec, got, want)
		}
	}
}

// TestParseTrailingAliasChain covers the README's flagship example: a chain
// whose tail is a registered alias, expanded inline.
func TestParseTrailingAliasChain(t *testing.T) {
	r := newTestRegistry(t)
	r.RegisterProvider(fake.New("ollama-cloud"))
	r.RegisterProvider(fake.New("anthropic"))
	r.RegisterProvider(fake.New("openai"))
	r.RegisterAlias("thinking", "openai/gpt-5.5,anthropic/opus-4.8")

	m, err := r.Parse("ollama-cloud/minimax-m3:cloud,ollama-cloud/kimi-k2.6:cloud,anthropic/opus-4.8,thinking")
	if err != nil {
		t.Fatalf("Parse: %v", err)
	}
	// "thinking" expands inline at the tail; its anthropic/opus-4.8 element
	// is a duplicate of the explicit one and is kept once (first wins).
	want := []string{
		"ollama-cloud/minimax-m3:cloud",
		"ollama-cloud/kimi-k2.6:cloud",
		"anthropic/opus-4.8",
		"openai/gpt-5.5",
	}
	if got := targetsOf(t, m); !slices.Equal(got, want) {
		t.Errorf("targets = %v, want %v", got, want)
	}
}

func TestParseAliasPositions(t *testing.T) {
	r := newTestRegistry(t)
	r.RegisterProvider(fake.New("fp"))
	r.RegisterAlias("mid", "fp/m1,fp/m2")

	m, err := r.Parse("fp/head,mid,fp/tail")
	if err != nil {
		t.Fatalf("Parse: %v", err)
	}
	want := []string{"fp/head", "fp/m1", "fp/m2", "fp/tail"}
	if got := targetsOf(t, m); !slices.Equal(got, want) {
		t.Errorf("targets = %v, want %v", got, want)
	}
}

func TestParseNestedAlias(t *testing.T) {
	r := newTestRegistry(t)
	r.RegisterProvider(fake.New("fp"))
	r.RegisterAlias("inner", "fp/deep")
	r.RegisterAlias("outer", "inner,fp/shallow")

	m, err := r.Parse("outer")
	if err != nil {
		t.Fatalf("Parse: %v", err)
	}
	want := []string{"fp/deep", "fp/shallow"}
	if got := targetsOf(t, m); !slices.Equal(got, want) {
		t.Errorf("targets = %v, want %v", got, want)
	}
}

func TestParseAliasCycle(t *testing.T) {
	r := newTestRegistry(t)
	r.RegisterAlias("a", "b")
	r.RegisterAlias("b", "a")
	if _, err := r.Parse("a"); !errors.Is(err, ErrAliasCycle) {
		t.Errorf("Parse(a) error = %v, want ErrAliasCycle", err)
	}

	r.RegisterAlias("self", "self")
	if _, err := r.Parse("self"); !errors.Is(err, ErrAliasCycle) {
		t.Errorf("Parse(self) error = %v, want ErrAliasCycle", err)
	}
}

func TestParseUnknownAlias(t *testing.T) {
	r := newTestRegistry(t)
	if _, err := r.Parse("nonesuch"); !errors.Is(err, ErrUnknownProvider) {
		t.Errorf("error = %v, want ErrUnknownProvider", err)
	}
}

func TestParseBareProviderName(t *testing.T) {
	r := newTestRegistry(t)
	_, err := r.Parse("openai")
	if err == nil || !strings.Contains(err.Error(), "openai/<model-id>") {
		t.Errorf("error = %v, want hint about openai/<model-id>", err)
	}
}

func TestParseUnknownProviderMentionsEnvVar(t *testing.T) {
	r := newTestRegistry(t)
	_, err := r.Parse("nope/some-model")
	if !errors.Is(err, ErrUnknownProvider) {
		t.Fatalf("error = %v, want ErrUnknownProvider", err)
	}
	if !strings.Contains(err.Error(), "LLM_NOPE") {
		t.Errorf("error %q should mention the LLM_NOPE env var", err)
	}
}

func TestParseEmptySpecs(t *testing.T) {
	r := newTestRegistry(t)
	for _, spec := range []string{"", "   ", ",", " , ,"} {
		if _, err := r.Parse(spec); !errors.Is(err, ErrEmptySpec) {
			t.Errorf("Parse(%q) error = %v, want ErrEmptySpec", spec, err)
		}
	}
}

func TestParseTrimsWhitespace(t *testing.T) {
	r := newTestRegistry(t)
	r.RegisterProvider(fake.New("fp"))
	m, err := r.Parse("  fp/a , fp/b  ")
	if err != nil {
		t.Fatalf("Parse: %v", err)
	}
	want := []string{"fp/a", "fp/b"}
	if got := targetsOf(t, m); !slices.Equal(got, want) {
		t.Errorf("targets = %v, want %v", got, want)
	}
}

func TestParseDeduplicatesElements(t *testing.T) {
	r := newTestRegistry(t)
	r.RegisterProvider(fake.New("fp"))
	m, err := r.Parse("fp/a,fp/b,fp/a")
	if err != nil {
		t.Fatalf("Parse: %v", err)
	}
	want := []string{"fp/a", "fp/b"}
	if got := targetsOf(t, m); !slices.Equal(got, want) {
		t.Errorf("targets = %v, want %v", got, want)
	}
}

func TestBuiltinsResolve(t *testing.T) {
	r := newTestRegistry(t)
	// All built-in provider names resolve even before their client
	// implementations land (stub providers error only on use).
	for _, name := range []string{"openai", "anthropic", "google", "ollama", "ollama-cloud", "foreman"} {
		if _, err := r.Parse(name + "/anything"); err != nil {
			t.Errorf("Parse(%s/anything): %v", name, err)
		}
	}
}