package run

import (
	"context"
	"encoding/json"
	"errors"
	"strings"
	"testing"

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

	"gitea.stevedudenhoeffer.com/steve/executus/tool"
)

// phaseProvider builds a fake provider scripted with the given per-call steps
// (consumed in order across every phase's model call) and a resolver over it,
// returning both so a test can read back each call's request.
func phaseProvider(t *testing.T, steps ...fake.Step) (ModelResolver, *fake.Provider) {
	t.Helper()
	fp := fake.New("fake")
	fp.Enqueue("test-model", steps...)
	m, err := fp.Model("test-model")
	if err != nil {
		t.Fatalf("fake model: %v", err)
	}
	return func(ctx context.Context, _ string) (context.Context, llm.Model, error) {
		return ctx, m, nil
	}, fp
}

// TestPhases_SequentialThreadsOutputs: phases run in order, each phase's output
// is threaded into the next via {{.<PhaseName>}}, {{.Query}} reaches a phase, and
// the final phase's output is the run output.
func TestPhases_SequentialThreadsOutputs(t *testing.T) {
	models, fp := phaseProvider(t,
		fake.Reply("out-a"),
		fake.Reply("out-b"),
		fake.Reply("out-c"),
	)
	ex := New(Config{Registry: tool.NewRegistry(), Models: models})

	ra := RunnableAgent{
		Name:      "pipeline",
		ModelTier: "test-model",
		Phases: []Phase{
			{Name: "a", SystemPrompt: "Phase A instructions"},
			{Name: "b", SystemPrompt: "B saw: {{.a}}"},
			{Name: "c", SystemPrompt: "C saw: {{.b}} and query {{.Query}}"},
		},
	}
	res := ex.Run(context.Background(), ra, tool.Invocation{RunID: "r", CallerID: "c"}, "QUERY-TEXT")
	if res.Err != nil {
		t.Fatalf("run error: %v", res.Err)
	}
	if res.Output != "out-c" {
		t.Fatalf("final output = %q, want the LAST phase's output out-c", res.Output)
	}
	calls := fp.Calls()
	if len(calls) != 3 {
		t.Fatalf("want 3 model calls (one per phase), got %d", len(calls))
	}
	if got := calls[0].Request.System; got != "Phase A instructions" {
		t.Errorf("phase a system = %q", got)
	}
	if got := calls[1].Request.System; got != "B saw: out-a" {
		t.Errorf("phase b should see phase a's output threaded; system = %q", got)
	}
	if got := calls[2].Request.System; got != "C saw: out-b and query QUERY-TEXT" {
		t.Errorf("phase c should see phase b's output + {{.Query}}; system = %q", got)
	}
}

// TestPhases_OptionalFailureSubstitutesFallback: an Optional phase that errors
// does not abort the pipeline — its FallbackMessage becomes its output and is
// threaded into later phases, which still run.
func TestPhases_OptionalFailureSubstitutesFallback(t *testing.T) {
	models, fp := phaseProvider(t,
		fake.Fail(errors.New("provider exploded")), // phase a fails
		fake.Reply("out-b"),                        // phase b runs
	)
	ex := New(Config{Registry: tool.NewRegistry(), Models: models})

	ra := RunnableAgent{
		Name:      "pipeline",
		ModelTier: "test-model",
		Phases: []Phase{
			{Name: "a", SystemPrompt: "Phase A", Optional: true, FallbackMessage: "FALLBACK-A"},
			{Name: "b", SystemPrompt: "B saw: {{.a}}"},
		},
	}
	res := ex.Run(context.Background(), ra, tool.Invocation{RunID: "r", CallerID: "c"}, "Q")
	if res.Err != nil {
		t.Fatalf("optional-phase failure must not fail the run: %v", res.Err)
	}
	if res.Output != "out-b" {
		t.Fatalf("final output = %q, want out-b", res.Output)
	}
	calls := fp.Calls()
	if len(calls) != 2 {
		t.Fatalf("want 2 calls (failed phase a + phase b), got %d", len(calls))
	}
	if got := calls[1].Request.System; got != "B saw: FALLBACK-A" {
		t.Errorf("phase b should see the fallback threaded; system = %q", got)
	}
}

// TestPhases_OptionalDoesNotSwallowCancellation: an Optional phase that fails
// with a context cancellation must NOT be swallowed into its FallbackMessage —
// the run genuinely ended (cancel/deadline/critic-kill) and must surface the
// error so the run is classified cancelled/timeout/killed, not "ok".
func TestPhases_OptionalDoesNotSwallowCancellation(t *testing.T) {
	models, _ := phaseProvider(t, fake.Fail(context.Canceled))
	ex := New(Config{Registry: tool.NewRegistry(), Models: models})

	ra := RunnableAgent{
		Name:      "pipeline",
		ModelTier: "test-model",
		Phases: []Phase{
			// IsRunFunc so the cancellation surfaces directly wrapped (%w).
			{Name: "a", SystemPrompt: "Phase A", IsRunFunc: true, Optional: true, FallbackMessage: "FB"},
		},
	}
	res := ex.Run(context.Background(), ra, tool.Invocation{RunID: "r", CallerID: "c"}, "Q")
	if !errors.Is(res.Err, context.Canceled) {
		t.Fatalf("Optional phase must NOT swallow a cancellation; res.Err = %v", res.Err)
	}
	if res.Output == "FB" {
		t.Error("a cancelled run must not report the fallback message as output")
	}
}

// TestPhases_DuplicateNamesBothRun: a fresh (non-resume) run with two phases
// sharing a name must run BOTH — the resume-skip guard keys off a separate
// resume set, not the live outputs map (which fills as phases run), so a phase
// never skips a same-named sibling on a fresh run.
func TestPhases_DuplicateNamesBothRun(t *testing.T) {
	models, fp := phaseProvider(t, fake.Reply("first"), fake.Reply("second"))
	ex := New(Config{Registry: tool.NewRegistry(), Models: models})
	ra := RunnableAgent{
		Name: "p", ModelTier: "test-model",
		Phases: []Phase{{Name: "x", SystemPrompt: "P1"}, {Name: "x", SystemPrompt: "P2"}},
	}
	res := ex.Run(context.Background(), ra, tool.Invocation{RunID: "r"}, "Q")
	if res.Err != nil {
		t.Fatalf("run error: %v", res.Err)
	}
	if n := len(fp.Calls()); n != 2 {
		t.Fatalf("both same-named phases must run on a fresh run; got %d model calls", n)
	}
}

// TestPhases_HardErrorAborts: a NON-optional phase that hits a hard error (not a
// budget/step exhaustion) aborts the pipeline; later phases do not run.
func TestPhases_HardErrorAborts(t *testing.T) {
	boom := errors.New("model down")
	models, fp := phaseProvider(t,
		fake.Fail(boom),     // phase a (non-optional) fails hard
		fake.Reply("out-b"), // must NOT be consumed
	)
	ex := New(Config{Registry: tool.NewRegistry(), Models: models})

	ra := RunnableAgent{
		Name:      "pipeline",
		ModelTier: "test-model",
		Phases: []Phase{
			{Name: "a", SystemPrompt: "Phase A"},
			{Name: "b", SystemPrompt: "Phase B"},
		},
	}
	res := ex.Run(context.Background(), ra, tool.Invocation{RunID: "r", CallerID: "c"}, "Q")
	if res.Err == nil {
		t.Fatal("a hard non-optional phase error must fail the run")
	}
	if !errors.Is(res.Err, boom) {
		t.Errorf("run error %v should wrap the phase's model error", res.Err)
	}
	if n := len(fp.Calls()); n != 1 {
		t.Errorf("pipeline must abort after phase a; got %d calls (phase b should not run)", n)
	}
}

// TestPhases_IsRunFuncBareCall: an IsRunFunc phase produces output via a bare LLM
// call and that output threads into a following loop phase.
func TestPhases_IsRunFuncBareCall(t *testing.T) {
	models, fp := phaseProvider(t,
		fake.Reply("plan-output"), // IsRunFunc phase a
		fake.Reply("final"),       // loop phase b
	)
	ex := New(Config{Registry: tool.NewRegistry(), Models: models})

	ra := RunnableAgent{
		Name:      "pipeline",
		ModelTier: "test-model",
		Phases: []Phase{
			{Name: "plan", SystemPrompt: "Make a plan for {{.Query}}", IsRunFunc: true},
			{Name: "exec", SystemPrompt: "Execute: {{.plan}}"},
		},
	}
	res := ex.Run(context.Background(), ra, tool.Invocation{RunID: "r", CallerID: "c"}, "do-thing")
	if res.Err != nil {
		t.Fatalf("run error: %v", res.Err)
	}
	if res.Output != "final" {
		t.Fatalf("output = %q, want final", res.Output)
	}
	calls := fp.Calls()
	if len(calls) != 2 {
		t.Fatalf("want 2 calls, got %d", len(calls))
	}
	if got := calls[0].Request.System; got != "Make a plan for do-thing" {
		t.Errorf("IsRunFunc phase system = %q", got)
	}
	if got := calls[1].Request.System; got != "Execute: plan-output" {
		t.Errorf("exec phase should see the plan output threaded; system = %q", got)
	}
}

// TestPhases_SystemHeaderAppliedPerPhase: the platform SystemHeader is prepended
// to every phase's prompt (each phase keeps it).
func TestPhases_SystemHeaderAppliedPerPhase(t *testing.T) {
	models, fp := phaseProvider(t, fake.Reply("a"), fake.Reply("b"))
	ex := New(Config{Registry: tool.NewRegistry(), Models: models, SystemHeader: "PLATFORM"})

	ra := RunnableAgent{
		Name:      "p",
		ModelTier: "test-model",
		Phases:    []Phase{{Name: "one", SystemPrompt: "P1"}, {Name: "two", SystemPrompt: "P2"}},
	}
	if res := ex.Run(context.Background(), ra, tool.Invocation{RunID: "r"}, "Q"); res.Err != nil {
		t.Fatalf("run error: %v", res.Err)
	}
	for i, want := range []string{"PLATFORM\n\nP1", "PLATFORM\n\nP2"} {
		if got := fp.Calls()[i].Request.System; got != want {
			t.Errorf("phase %d system = %q, want %q", i, got, want)
		}
	}
}

// TestFilterToolbox: a named subset restricts the toolbox (preserving order);
// empty names = the full palette; unknown names are skipped.
func TestFilterToolbox(t *testing.T) {
	box := llm.NewToolbox("base")
	noop := func(context.Context, json.RawMessage) (any, error) { return "", nil }
	for _, name := range []string{"alpha", "beta", "gamma"} {
		if err := box.Add(llm.Tool{Name: name, Description: "d", Handler: noop}); err != nil {
			t.Fatalf("add %s: %v", name, err)
		}
	}

	full := filterToolbox(box, nil)
	if len(full.Tools()) != 3 {
		t.Errorf("nil names = full palette; got %d tools", len(full.Tools()))
	}

	sub := filterToolbox(box, []string{"gamma", "alpha", "nonexistent"})
	names := make([]string, 0)
	for _, tl := range sub.Tools() {
		names = append(names, tl.Name)
	}
	if strings.Join(names, ",") != "gamma,alpha" {
		t.Errorf("subset (order-preserving, unknown skipped) = %v, want [gamma alpha]", names)
	}
}

// TestExpandPhaseTemplate: {{.Query}} + prior outputs substitute; a parse error
// returns the template unchanged (best-effort).
func TestExpandPhaseTemplate(t *testing.T) {
	got := expandPhaseTemplate("q={{.Query}} a={{.a}}", "QQ", map[string]string{"a": "AA"})
	if got != "q=QQ a=AA" {
		t.Errorf("expand = %q", got)
	}
	// Malformed template → returned unchanged.
	bad := "{{.Unclosed"
	if expandPhaseTemplate(bad, "QQ", nil) != bad {
		t.Errorf("malformed template should pass through unchanged")
	}
}