// Copyright 2024 Google Inc. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package blueprint

import (
	"fmt"
	"slices"
	"strings"
	"testing"
)

func testTransition(bp string) (*Context, []error) {
	ctx := newContext()
	ctx.MockFileSystem(map[string][]byte{
		"Android.bp": []byte(bp),
	})

	ctx.RegisterBottomUpMutator("deps", depsMutator)
	ctx.RegisterTransitionMutator("transition", transitionTestMutator{})
	ctx.RegisterBottomUpMutator("post_transition_deps", postTransitionDepsMutator)

	ctx.RegisterModuleType("transition_module", newTransitionModule)
	_, errs := ctx.ParseBlueprintsFiles("Android.bp", nil)
	if len(errs) > 0 {
		return nil, errs
	}

	_, errs = ctx.ResolveDependencies(nil)
	if len(errs) > 0 {
		return nil, errs
	}

	return ctx, nil
}

func assertNoErrors(t *testing.T, errs []error) {
	t.Helper()
	if len(errs) > 0 {
		t.Errorf("unexpected errors:")
		for _, err := range errs {
			t.Errorf("  %s", err)
		}
		t.FailNow()
	}
}

const testTransitionBp = `
			transition_module {
			    name: "A",
			    deps: ["B", "C"],
				split: ["b", "a"],
			}

			transition_module {
				name: "B",
				deps: ["C"],
				outgoing: "c",
				%s
			}

			transition_module {
				name: "C",
				deps: ["D"],
			}

			transition_module {
				name: "D",
				incoming: "d",
				deps: ["E"],
			}

			transition_module {
				name: "E",
			}

			transition_module {
				name: "F"
			}
		`

func getTransitionModule(ctx *Context, name, variant string) *transitionModule {
	group := ctx.moduleGroupFromName(name, nil)
	module := group.moduleOrAliasByVariantName(variant).module()
	return module.logicModule.(*transitionModule)
}

func checkTransitionVariants(t *testing.T, ctx *Context, name string, expectedVariants []string) {
	t.Helper()
	group := ctx.moduleGroupFromName(name, nil)
	var gotVariants []string
	for _, variant := range group.modules {
		gotVariants = append(gotVariants, variant.moduleOrAliasVariant().variations["transition"])
	}
	if !slices.Equal(expectedVariants, gotVariants) {
		t.Errorf("expected variants of %q to be %q, got %q", name, expectedVariants, gotVariants)
	}
}

func checkTransitionDeps(t *testing.T, ctx *Context, m Module, expected ...string) {
	t.Helper()
	var got []string
	ctx.VisitDirectDeps(m, func(m Module) {
		got = append(got, ctx.ModuleName(m)+"("+ctx.ModuleSubDir(m)+")")
	})
	if !slices.Equal(got, expected) {
		t.Errorf("unexpected %q dependencies, got %q expected %q",
			ctx.ModuleName(m), got, expected)
	}
}

func checkTransitionMutate(t *testing.T, m *transitionModule, variant string) {
	t.Helper()
	if m.properties.Mutated != variant {
		t.Errorf("unexpected mutated property in %q, expected %q got %q", m.Name(), variant, m.properties.Mutated)
	}
}

func TestTransition(t *testing.T) {
	ctx, errs := testTransition(fmt.Sprintf(testTransitionBp, ""))
	assertNoErrors(t, errs)

	// Module A uses Split to create a and b variants
	checkTransitionVariants(t, ctx, "A", []string{"b", "a"})
	// Module B inherits a and b variants from A
	checkTransitionVariants(t, ctx, "B", []string{"", "a", "b"})
	// Module C inherits a and b variants from A, but gets an outgoing c variant from B
	checkTransitionVariants(t, ctx, "C", []string{"", "a", "b", "c"})
	// Module D always has incoming variant d
	checkTransitionVariants(t, ctx, "D", []string{"", "d"})
	// Module E inherits d from D
	checkTransitionVariants(t, ctx, "E", []string{"", "d"})
	// Module F is untouched
	checkTransitionVariants(t, ctx, "F", []string{""})

	A_a := getTransitionModule(ctx, "A", "a")
	A_b := getTransitionModule(ctx, "A", "b")
	B_a := getTransitionModule(ctx, "B", "a")
	B_b := getTransitionModule(ctx, "B", "b")
	C_a := getTransitionModule(ctx, "C", "a")
	C_b := getTransitionModule(ctx, "C", "b")
	C_c := getTransitionModule(ctx, "C", "c")
	D_d := getTransitionModule(ctx, "D", "d")
	E_d := getTransitionModule(ctx, "E", "d")
	F := getTransitionModule(ctx, "F", "")

	checkTransitionDeps(t, ctx, A_a, "B(a)", "C(a)")
	checkTransitionDeps(t, ctx, A_b, "B(b)", "C(b)")
	checkTransitionDeps(t, ctx, B_a, "C(c)")
	checkTransitionDeps(t, ctx, B_b, "C(c)")
	checkTransitionDeps(t, ctx, C_a, "D(d)")
	checkTransitionDeps(t, ctx, C_b, "D(d)")
	checkTransitionDeps(t, ctx, C_c, "D(d)")
	checkTransitionDeps(t, ctx, D_d, "E(d)")
	checkTransitionDeps(t, ctx, E_d)
	checkTransitionDeps(t, ctx, F)

	checkTransitionMutate(t, A_a, "a")
	checkTransitionMutate(t, A_b, "b")
	checkTransitionMutate(t, B_a, "a")
	checkTransitionMutate(t, B_b, "b")
	checkTransitionMutate(t, C_a, "a")
	checkTransitionMutate(t, C_b, "b")
	checkTransitionMutate(t, C_c, "c")
	checkTransitionMutate(t, D_d, "d")
	checkTransitionMutate(t, E_d, "d")
	checkTransitionMutate(t, F, "")
}

func TestPostTransitionDeps(t *testing.T) {
	ctx, errs := testTransition(fmt.Sprintf(testTransitionBp,
		`post_transition_deps: ["C", "D:late", "E:d", "F"],`))
	assertNoErrors(t, errs)

	// Module A uses Split to create a and b variants
	checkTransitionVariants(t, ctx, "A", []string{"b", "a"})
	// Module B inherits a and b variants from A
	checkTransitionVariants(t, ctx, "B", []string{"", "a", "b"})
	// Module C inherits a and b variants from A, but gets an outgoing c variant from B
	checkTransitionVariants(t, ctx, "C", []string{"", "a", "b", "c"})
	// Module D always has incoming variant d
	checkTransitionVariants(t, ctx, "D", []string{"", "d"})
	// Module E inherits d from D
	checkTransitionVariants(t, ctx, "E", []string{"", "d"})
	// Module F is untouched
	checkTransitionVariants(t, ctx, "F", []string{""})

	A_a := getTransitionModule(ctx, "A", "a")
	A_b := getTransitionModule(ctx, "A", "b")
	B_a := getTransitionModule(ctx, "B", "a")
	B_b := getTransitionModule(ctx, "B", "b")
	C_a := getTransitionModule(ctx, "C", "a")
	C_b := getTransitionModule(ctx, "C", "b")
	C_c := getTransitionModule(ctx, "C", "c")
	D_d := getTransitionModule(ctx, "D", "d")
	E_d := getTransitionModule(ctx, "E", "d")
	F := getTransitionModule(ctx, "F", "")

	checkTransitionDeps(t, ctx, A_a, "B(a)", "C(a)")
	checkTransitionDeps(t, ctx, A_b, "B(b)", "C(b)")
	// Verify post-mutator dependencies added to B.  The first C(c) is a pre-mutator dependency.
	//  C(c) was added by C and rewritten by OutgoingTransition on B
	//  D(d) was added by D:late and rewritten by IncomingTransition on D
	//  E(d) was added by E:d
	//  F() was added by F, and ignored the existing variation on B
	checkTransitionDeps(t, ctx, B_a, "C(c)", "C(c)", "D(d)", "E(d)", "F()")
	checkTransitionDeps(t, ctx, B_b, "C(c)", "C(c)", "D(d)", "E(d)", "F()")
	checkTransitionDeps(t, ctx, C_a, "D(d)")
	checkTransitionDeps(t, ctx, C_b, "D(d)")
	checkTransitionDeps(t, ctx, C_c, "D(d)")
	checkTransitionDeps(t, ctx, D_d, "E(d)")
	checkTransitionDeps(t, ctx, E_d)
	checkTransitionDeps(t, ctx, F)

	checkTransitionMutate(t, A_a, "a")
	checkTransitionMutate(t, A_b, "b")
	checkTransitionMutate(t, B_a, "a")
	checkTransitionMutate(t, B_b, "b")
	checkTransitionMutate(t, C_a, "a")
	checkTransitionMutate(t, C_b, "b")
	checkTransitionMutate(t, C_c, "c")
	checkTransitionMutate(t, D_d, "d")
	checkTransitionMutate(t, E_d, "d")
	checkTransitionMutate(t, F, "")
}

func TestPostTransitionDepsMissingVariant(t *testing.T) {
	// TODO: eventually this will create the missing variant on demand
	_, errs := testTransition(fmt.Sprintf(testTransitionBp,
		`post_transition_deps: ["E:missing"],`))
	expectedError := `Android.bp:8:4: dependency "E" of "B" missing variant:
  transition:missing
available variants:
  transition:
  transition:d`
	if len(errs) != 1 || errs[0].Error() != expectedError {
		t.Errorf("expected error %q, got %q", expectedError, errs)
	}
}

type transitionTestMutator struct{}

func (transitionTestMutator) Split(ctx BaseModuleContext) []string {
	if split := ctx.Module().(*transitionModule).properties.Split; len(split) > 0 {
		return split
	}
	return []string{""}
}

func (transitionTestMutator) OutgoingTransition(ctx OutgoingTransitionContext, sourceVariation string) string {
	if outgoing := ctx.Module().(*transitionModule).properties.Outgoing; outgoing != nil {
		return *outgoing
	}
	return sourceVariation
}

func (transitionTestMutator) IncomingTransition(ctx IncomingTransitionContext, incomingVariation string) string {
	if incoming := ctx.Module().(*transitionModule).properties.Incoming; incoming != nil {
		return *incoming
	}
	return incomingVariation
}

func (transitionTestMutator) Mutate(ctx BottomUpMutatorContext, variation string) {
	ctx.Module().(*transitionModule).properties.Mutated = variation
}

type transitionModule struct {
	SimpleName
	properties struct {
		Deps                 []string
		Post_transition_deps []string
		Split                []string
		Outgoing             *string
		Incoming             *string

		Mutated string `blueprint:"mutated"`
	}
}

func newTransitionModule() (Module, []interface{}) {
	m := &transitionModule{}
	return m, []interface{}{&m.properties, &m.SimpleName.Properties}
}

func (f *transitionModule) GenerateBuildActions(ModuleContext) {
}

func (f *transitionModule) Deps() []string {
	return f.properties.Deps
}

func (f *transitionModule) IgnoreDeps() []string {
	return nil
}

func postTransitionDepsMutator(mctx BottomUpMutatorContext) {
	if m, ok := mctx.Module().(*transitionModule); ok {
		for _, dep := range m.properties.Post_transition_deps {
			module, variation, _ := strings.Cut(dep, ":")
			var variations []Variation
			if variation != "" {
				variations = append(variations, Variation{"transition", variation})
			}
			mctx.AddVariationDependencies(variations, walkerDepsTag{follow: true}, module)
		}
	}
}