package workflow_test

// audit_fixes_test.go covers all P0 / P1 items identified in the external audit:
//
//  P0-5  Branch_* no-match without ELSE → continue to Branch_*.next (not error)
//  P0-3  Validate: Stop_* must not have next or children
//  P0-2  Validate: reference integrity, entry≥1, reachability
//  P0-1  executeWorkflow: start from true entry nodes (not always steps[0])
//  P0-7  registry.params: name(TYPE) = defaultValue syntax + default application
//  P0-4  ExecuteWithRunParams + RunParams stored on context
//  P1-1  Resume on non-paused workflow → error; best-effort pause_rejected event

import (
	"context"
	"strings"
	"testing"
	"time"

	"workflow"
)

// ── helpers ───────────────────────────────────────────────────────────────────

func auditRegistry() workflow.Registry {
	return workflow.Registry{
		Services:   []string{},
		Components: []string{},
		Vars:       []string{"$out(ANY)"},
	}
}

func auditAdapters() *workflow.Adapters {
	return &workflow.Adapters{
		Service:   workflow.NewDefaultServiceAdapter(),
		Component: workflow.NewDefaultComponentAdapter(),
		LLM:       workflow.NewDefaultLLMAdapter(),
	}
}

func wantValidationError(t *testing.T, wf *workflow.Workflow, fragment string) {
	t.Helper()
	_, err := workflow.NewEngine(wf)
	if err == nil {
		t.Fatal("expected validation error, got nil")
	}
	if fragment != "" && !strings.Contains(err.Error(), fragment) {
		t.Fatalf("expected error containing %q, got: %v", fragment, err)
	}
}

// runAndDrain executes the workflow, drains the event stream, and returns the context.
func runAndDrain(t *testing.T, eng *workflow.Engine, initialVars map[string]interface{}) *workflow.ExecutionContext {
	t.Helper()
	result, err := eng.Execute(context.Background(), initialVars, auditAdapters())
	if err != nil {
		t.Fatalf("Execute: %v", err)
	}
	for range result.RunEventStream {
	}
	return result.Context
}

// ── P0-5: Branch_* no-match without ELSE → continue to Branch_*.next ─────────

// TestBranchNoMatchContinuesToNext verifies that when a Branch_* step has no
// matching case and no ELSE clause, execution proceeds to Branch_*.next rather
// than returning an error (spec §10.10).
func TestBranchNoMatchContinuesToNext(t *testing.T) {
	reg := auditRegistry()
	reg.Params = []string{"score(INT)"}
	wf := &workflow.Workflow{
		Version:  "3.15",
		Name:     "BranchNoMatch",
		Registry: reg,
		Steps: []workflow.Step{
			{
				ID:    "Branch_check",
				Next:  "Set_done",
				Cases: [][]string{{"=score > 90", "Set_high"}},
				// No ELSE — if score ≤ 90, should skip to Branch_check.next
			},
			// Branch target (only executed if score > 90)
			{ID: "Set_high", Target: "$out", Value: "high", Next: "Set_done"},
			// Normal continuation after Branch_check
			{ID: "Set_done", Target: "$out", Value: "done", Next: "Stop_end"},
			{ID: "Stop_end"},
		},
	}

	eng, err := workflow.NewEngine(wf)
	if err != nil {
		t.Fatalf("NewEngine: %v", err)
	}
	ctx := runAndDrain(t, eng, map[string]interface{}{"score": int64(50)})

	// $out should be "done" (Set_done was reached; Set_high was NOT executed)
	if got := ctx.Variables["$out"]; got != "done" {
		t.Errorf("expected $out == 'done', got %v", got)
	}
}

// TestBranchElseFallback verifies that when ELSE is present, it is used
// (regression guard for existing ELSE behaviour).
func TestBranchElseFallback(t *testing.T) {
	reg := auditRegistry()
	reg.Params = []string{"score(INT)"}
	wf := &workflow.Workflow{
		Version:  "3.15",
		Name:     "BranchElse",
		Registry: reg,
		Steps: []workflow.Step{
			{
				ID:   "Branch_check",
				Next: "Stop_end",
				Cases: [][]string{
					{"=score > 90", "Set_high"},
					{"ELSE", "Set_low"},
				},
			},
			{ID: "Set_high", Target: "$out", Value: "high", Next: "Stop_end"},
			{ID: "Set_low", Target: "$out", Value: "low", Next: "Stop_end"},
			{ID: "Stop_end"},
		},
	}

	eng, err := workflow.NewEngine(wf)
	if err != nil {
		t.Fatalf("NewEngine: %v", err)
	}
	ctx := runAndDrain(t, eng, map[string]interface{}{"score": int64(50)})
	if got := ctx.Variables["$out"]; got != "low" {
		t.Errorf("expected $out == 'low', got %v", got)
	}
}

// ── P0-3: Validate Stop_* constraints ────────────────────────────────────────

func TestValidateStopWithNext(t *testing.T) {
	wf := &workflow.Workflow{
		Version:  "3.15",
		Name:     "StopWithNext",
		Registry: auditRegistry(),
		Steps: []workflow.Step{
			{ID: "Noop_start", Next: "Stop_end"},
			{ID: "Stop_end", Next: "Noop_start"}, // INVALID: Stop_* cannot have next
		},
	}
	wantValidationError(t, wf, "Stop_end")
}

func TestValidateStopWithChildren(t *testing.T) {
	wf := &workflow.Workflow{
		Version:  "3.15",
		Name:     "StopWithChildren",
		Registry: auditRegistry(),
		Steps: []workflow.Step{
			{ID: "Noop_start", Next: "Stop_end"},
			{ID: "Noop_child", Next: "RETURN"},
			{ID: "Stop_end", Children: []string{"Noop_child"}}, // INVALID
		},
	}
	wantValidationError(t, wf, "children")
}

// ── P0-2: Reference integrity ─────────────────────────────────────────────────

func TestValidateDeadNextReference(t *testing.T) {
	wf := &workflow.Workflow{
		Version:  "3.15",
		Name:     "DeadNext",
		Registry: auditRegistry(),
		Steps: []workflow.Step{
			{ID: "Noop_start", Next: "Stop_nonexistent"}, // INVALID: step doesn't exist
		},
	}
	wantValidationError(t, wf, "Stop_nonexistent")
}

func TestValidateDeadChildReference(t *testing.T) {
	wf := &workflow.Workflow{
		Version:  "3.15",
		Name:     "DeadChild",
		Registry: auditRegistry(),
		Steps: []workflow.Step{
			{ID: "Noop_start", Children: []string{"Noop_ghost"}, Next: "Stop_end"},
			{ID: "Stop_end"},
		},
	}
	wantValidationError(t, wf, "Noop_ghost")
}

func TestValidateDeadCaseReference(t *testing.T) {
	wf := &workflow.Workflow{
		Version:  "3.15",
		Name:     "DeadCase",
		Registry: auditRegistry(),
		Steps: []workflow.Step{
			{ID: "Branch_check", Next: "Stop_end", Cases: [][]string{{"=1==1", "Set_ghost"}}},
			{ID: "Stop_end"},
		},
	}
	wantValidationError(t, wf, "Set_ghost")
}

func TestValidateDeadOnErrorReference(t *testing.T) {
	wf := &workflow.Workflow{
		Version:  "3.15",
		Name:     "DeadOnError",
		Registry: auditRegistry(),
		Steps: []workflow.Step{
			{ID: "Noop_start", Next: "Stop_end", OnError: "Stop_missing"},
			{ID: "Stop_end"},
		},
	}
	wantValidationError(t, wf, "Stop_missing")
}

// ── P0-2: Entry node and reachability ─────────────────────────────────────────

// TestValidateNoEntryNode verifies that a self-referencing step (all steps
// referenced) is rejected because there is no entry node.
func TestValidateNoEntryNode(t *testing.T) {
	// Noop_selfref.next = Noop_selfref: the only step references itself,
	// so no step is "unreferenced" → no entry node.
	wf := &workflow.Workflow{
		Version:  "3.15",
		Name:     "NoEntry",
		Registry: auditRegistry(),
		Steps: []workflow.Step{
			{ID: "Noop_selfref", Next: "Noop_selfref"},
		},
	}
	wantValidationError(t, wf, "entry node")
}

// TestValidateUnreachableStep verifies that a disconnected cycle is rejected
// because its steps are unreachable from the live graph's entry node.
func TestValidateUnreachableStep(t *testing.T) {
	// Noop_dead1 → Noop_dead2 → Noop_dead1 forms a disconnected cycle.
	// Noop_dead1 is referenced by Noop_dead2 (not entry).
	// Noop_dead2 is referenced by Noop_dead1 (not entry).
	// Only Noop_start is the entry node. BFS from Noop_start reaches
	// only Stop_end. Noop_dead1 and Noop_dead2 are unreachable.
	wf := &workflow.Workflow{
		Version:  "3.15",
		Name:     "Unreachable",
		Registry: auditRegistry(),
		Steps: []workflow.Step{
			{ID: "Noop_start", Next: "Stop_end"},
			{ID: "Stop_end"},
			{ID: "Noop_dead1", Next: "Noop_dead2"},
			{ID: "Noop_dead2", Next: "Noop_dead1"},
		},
	}
	wantValidationError(t, wf, "unreachable")
}

// ── P0-1: Entry node detection ────────────────────────────────────────────────

// TestEntryNodeNotFirstStep verifies that when steps[0] is referenced by
// another step, the engine correctly starts from the true entry node.
func TestEntryNodeNotFirstStep(t *testing.T) {
	// steps[0] = Set_middle  (referenced by Set_entry.next → NOT the entry node)
	// steps[1] = Set_entry   (not referenced → TRUE entry node)
	// steps[2] = Stop_end    (referenced by Set_middle.next)
	//
	// Correct execution: Set_entry ("entry") → Set_middle ("middle") → Stop_end
	// Final $out = "middle" (Set_middle is the last write).
	// If the engine wrongly starts from steps[0]=Set_middle, $out would end up
	// as "middle" too — but $out would never be "entry" first.
	// To distinguish, verify execution path by checking $out == "middle" AND
	// that Set_entry DID run (its write "entry" was overwritten by "middle").
	reg := auditRegistry()
	reg.Vars = []string{"$out(ANY)", "$trace(ANY)"}
	wf := &workflow.Workflow{
		Version:  "3.15",
		Name:     "EntryNotFirst",
		Registry: reg,
		Steps: []workflow.Step{
			// steps[0]: referenced by Set_entry.next → NOT entry
			{ID: "Set_middle", Target: "$out", Value: "middle", Next: "Stop_end"},
			// steps[1]: not referenced → TRUE entry
			{ID: "Set_entry", Target: "$out", Value: "entry", Next: "Set_middle"},
			{ID: "Stop_end"},
		},
	}

	eng, err := workflow.NewEngine(wf)
	if err != nil {
		t.Fatalf("NewEngine: %v", err)
	}
	ctx := runAndDrain(t, eng, nil)

	// Set_entry writes "entry", then Set_middle overwrites with "middle".
	// Final value = "middle", confirming execution started from the true entry node.
	if got := ctx.Variables["$out"]; got != "middle" {
		t.Errorf("$out = %v, want 'middle' (true entry: Set_entry → Set_middle)", got)
	}
}

// ── P0-7: Registry param defaults ─────────────────────────────────────────────

func TestParseParamDeclaration_INT_Default(t *testing.T) {
	decl, err := workflow.ParseParamDeclaration("maxRetries(INT) = 3")
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if decl.Name != "maxRetries" {
		t.Errorf("Name = %q, want 'maxRetries'", decl.Name)
	}
	if decl.Type != "INT" {
		t.Errorf("Type = %q, want 'INT'", decl.Type)
	}
	if decl.Default == nil || *decl.Default != "3" {
		t.Errorf("Default = %v, want ptr to '3'", decl.Default)
	}
}

func TestParseParamDeclaration_BOOL_Default(t *testing.T) {
	decl, err := workflow.ParseParamDeclaration("enabled(BOOL) = true")
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if decl.Default == nil || *decl.Default != "true" {
		t.Errorf("Default = %v, want ptr to 'true'", decl.Default)
	}
}

func TestParseParamDeclaration_STRING_Default(t *testing.T) {
	// String literals in declarations use surrounding double quotes.
	decl, err := workflow.ParseParamDeclaration(`prefix(STRING) = "hello"`)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	// ParseParamDeclaration strips the surrounding double quotes.
	if decl.Default == nil || *decl.Default != "hello" {
		t.Errorf("Default = %v, want ptr to 'hello' (quotes stripped)", decl.Default)
	}
}

func TestParseParamDeclaration_NoDefault(t *testing.T) {
	decl, err := workflow.ParseParamDeclaration("userId(STRING)")
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if decl.Default != nil {
		t.Errorf("Default should be nil, got %q", *decl.Default)
	}
}

func TestCoerceParamDefault_INT(t *testing.T) {
	raw := "5"
	decl := &workflow.ParamDeclaration{Name: "n", Type: "INT", Default: &raw}
	v, err := workflow.CoerceParamDefault(decl)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if v != int64(5) {
		t.Errorf("CoerceParamDefault = %v (%T), want int64(5)", v, v)
	}
}

func TestCoerceParamDefault_BOOL(t *testing.T) {
	raw := "false"
	decl := &workflow.ParamDeclaration{Name: "flag", Type: "BOOL", Default: &raw}
	v, err := workflow.CoerceParamDefault(decl)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if v != false {
		t.Errorf("CoerceParamDefault = %v, want false", v)
	}
}

func TestCoerceParamDefault_STRING(t *testing.T) {
	raw := "hello"
	decl := &workflow.ParamDeclaration{Name: "s", Type: "STRING", Default: &raw}
	v, err := workflow.CoerceParamDefault(decl)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if v != "hello" {
		t.Errorf("CoerceParamDefault = %v, want 'hello'", v)
	}
}

func TestCoerceParamDefault_Nil(t *testing.T) {
	decl := &workflow.ParamDeclaration{Name: "n", Type: "INT", Default: nil}
	v, err := workflow.CoerceParamDefault(decl)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if v != nil {
		t.Errorf("CoerceParamDefault = %v, want nil", v)
	}
}

// TestParamDefaultApplied verifies that when a registry param has a default and
// the caller does NOT provide it, the coerced default is applied to execCtx.Params.
func TestParamDefaultApplied(t *testing.T) {
	reg := workflow.Registry{
		Services:   []string{},
		Components: []string{},
		Vars:       []string{"$out(ANY)"},
		Params:     []string{"retries(INT) = 3"},
	}
	wf := &workflow.Workflow{
		Version:  "3.15",
		Name:     "DefaultParam",
		Registry: reg,
		Steps: []workflow.Step{
			// Write the retries param value to $out so we can inspect it.
			{ID: "Set_out", Target: "$out", Value: "=retries", Next: "Stop_end"},
			{ID: "Stop_end"},
		},
	}
	eng, err := workflow.NewEngine(wf)
	if err != nil {
		t.Fatalf("NewEngine: %v", err)
	}
	ctx := runAndDrain(t, eng, nil /* no initialVars — default should apply */)

	// Default is int64(3)
	if got := ctx.Variables["$out"]; got != int64(3) {
		t.Errorf("$out = %v (%T), want int64(3) (default value applied)", got, got)
	}
}

// TestParamDefaultNotOverridden verifies that an explicit caller value wins.
func TestParamDefaultNotOverridden(t *testing.T) {
	reg := workflow.Registry{
		Services:   []string{},
		Components: []string{},
		Vars:       []string{"$out(ANY)"},
		Params:     []string{"retries(INT) = 3"},
	}
	wf := &workflow.Workflow{
		Version:  "3.15",
		Name:     "DefaultParamOverride",
		Registry: reg,
		Steps: []workflow.Step{
			{ID: "Set_out", Target: "$out", Value: "=retries", Next: "Stop_end"},
			{ID: "Stop_end"},
		},
	}
	eng, err := workflow.NewEngine(wf)
	if err != nil {
		t.Fatalf("NewEngine: %v", err)
	}
	ctx := runAndDrain(t, eng, map[string]interface{}{"retries": int64(10)})

	if got := ctx.Variables["$out"]; got != int64(10) {
		t.Errorf("$out = %v, want int64(10) (caller value must override default)", got)
	}
}

// ── P0-4: RunParams + ExecuteWithRunParams ────────────────────────────────────

func TestExecuteWithRunParams_Stored(t *testing.T) {
	reg := auditRegistry()
	wf := &workflow.Workflow{
		Version:  "3.15",
		Name:     "RunParamsTest",
		Registry: reg,
		Steps: []workflow.Step{
			{ID: "Noop_start", Next: "Stop_end"},
			{ID: "Stop_end"},
		},
	}
	eng, err := workflow.NewEngine(wf)
	if err != nil {
		t.Fatalf("NewEngine: %v", err)
	}

	runParams := workflow.RunParams{
		WorkspaceID: "ws-42",
		Mode:        "test",
		Nodes:       []string{"Noop_start"},
	}

	result, execErr := eng.ExecuteWithRunParams(context.Background(), nil, auditAdapters(), runParams)
	if execErr != nil {
		t.Fatalf("ExecuteWithRunParams: %v", execErr)
	}
	for range result.RunEventStream {
	}

	rp := result.Context.RunParams
	if rp == nil {
		t.Fatal("RunParams is nil on context")
	}
	if rp.WorkspaceID != "ws-42" {
		t.Errorf("WorkspaceID = %q, want 'ws-42'", rp.WorkspaceID)
	}
	if rp.Mode != "test" {
		t.Errorf("Mode = %q, want 'test'", rp.Mode)
	}
	if len(rp.Nodes) != 1 || rp.Nodes[0] != "Noop_start" {
		t.Errorf("Nodes = %v, want ['Noop_start']", rp.Nodes)
	}
}

// ── P1-1: Resume on non-paused → error (spec §11.5.4) ─────────────────────────

// TestResumeNotPausedReturnsError verifies that calling Resume when the workflow
// is not in paused state (or has already completed) returns an error.
// The implementation also emits a best-effort pause_rejected event (spec §11.5.4);
// observability of that event is timing-dependent and not asserted here.
func TestResumeNotPausedReturnsError(t *testing.T) {
	reg := auditRegistry()
	wf := &workflow.Workflow{
		Version:  "3.15",
		Name:     "NotPausedReject",
		Registry: reg,
		Steps: []workflow.Step{
			{ID: "Noop_start", Next: "Stop_end"},
			{ID: "Stop_end"},
		},
	}
	eng, err := workflow.NewEngine(wf)
	if err != nil {
		t.Fatalf("NewEngine: %v", err)
	}
	result, execErr := eng.Execute(context.Background(), nil, auditAdapters())
	if execErr != nil {
		t.Fatalf("Execute: %v", execErr)
	}

	// Drain stream (workflow completes) before calling Resume.
	for range result.RunEventStream {
	}

	resumeErr := eng.Resume(result.Context, workflow.ResumeRequest{
		Token:     "any-token",
		RequestID: "req-001",
	})
	if resumeErr == nil {
		t.Fatal("expected error from Resume on non-paused workflow, got nil")
	}
	if !strings.Contains(resumeErr.Error(), "paused") {
		t.Errorf("error = %q, want it to mention 'paused'", resumeErr.Error())
	}
}

// TestResumeNotPausedEmitsPauseRejected verifies the pause_rejected event IS
// emitted when Resume is called on a paused workflow with an invalid token.
// The workflow has a short timeout so it terminates automatically without needing
// the correct token. This ensures deterministic timing.
func TestResumeNotPausedEmitsPauseRejected(t *testing.T) {
	reg := v315Registry()
	wf := &workflow.Workflow{
		Version:  "3.15",
		Name:     "PauseRejectedEvent",
		Registry: reg,
		Steps: []workflow.Step{
			{
				ID:                 "Pause_wait",
				ResumeResultTarget: "$result",
				Next:               "Stop_end",
				// Short timeout so the workflow self-terminates after the bad Resume call.
				Timeout: &workflow.PauseTimeout{Sec: 2, On: "Stop_timeout"},
			},
			{ID: "Stop_end"},
			{ID: "Stop_timeout"},
		},
	}
	eng := mustEngineV315(t, wf)
	result, execErr := eng.Execute(context.Background(), nil, v315Adapters())
	if execErr != nil {
		t.Fatalf("Execute: %v", execErr)
	}

	// Collect ALL events in the background goroutine.
	evtCh := make(chan []workflow.RunEvent, 1)
	go func() {
		var evs []workflow.RunEvent
		for ev := range result.RunEventStream {
			evs = append(evs, ev)
		}
		evtCh <- evs
	}()

	// Wait for workflow to pause (stream still open, PauseState set).
	if !waitForStatus(result.Context, workflow.StatusPaused, 2*time.Second) {
		t.Fatal("workflow did not reach paused state in time")
	}

	// Call Resume with an invalid token → engine emits pause_rejected(invalid_token)
	// to the open stream, which the background goroutine will capture.
	badErr := eng.Resume(result.Context, workflow.ResumeRequest{
		Token:     "wrong-token-xyz",
		RequestID: "req-bad-001",
	})
	if badErr == nil {
		t.Fatal("expected error for invalid token, got nil")
	}

	// Wait for the workflow to complete (it will self-terminate via the 2s timeout).
	allEvents := <-evtCh

	// Check that pause_rejected(invalid_token) was emitted.
	var rejected *workflow.RunEvent
	for i := range allEvents {
		if allEvents[i].Type == workflow.RunEventPauseRejected {
			rejected = &allEvents[i]
			break
		}
	}
	if rejected == nil {
		t.Fatal("expected pause_rejected event in stream, none found")
	}
	if rc, _ := rejected.Payload["reasonCode"].(string); rc != "invalid_token" {
		t.Errorf("reasonCode = %q, want 'invalid_token'", rc)
	}
}