// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package vta

import (
	"testing"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/buildssa"
	"golang.org/x/tools/go/callgraph/cha"
	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/go/ssa/ssautil"
)

func TestVTACallGraph(t *testing.T) {
	for _, file := range []string{
		"testdata/src/callgraph_static.go",
		"testdata/src/callgraph_ho.go",
		"testdata/src/callgraph_interfaces.go",
		"testdata/src/callgraph_pointers.go",
		"testdata/src/callgraph_collections.go",
		"testdata/src/callgraph_fields.go",
		"testdata/src/callgraph_field_funcs.go",
	} {
		t.Run(file, func(t *testing.T) {
			prog, want, err := testProg(file)
			if err != nil {
				t.Fatalf("couldn't load test file '%s': %s", file, err)
			}
			if len(want) == 0 {
				t.Fatalf("couldn't find want in `%s`", file)
			}

			g := CallGraph(ssautil.AllFunctions(prog), cha.CallGraph(prog))
			if got := callGraphStr(g); !subGraph(want, got) {
				t.Errorf("computed callgraph %v should contain %v", got, want)
			}
		})
	}
}

// TestVTAProgVsFuncSet exemplifies and tests different possibilities
// enabled by having an arbitrary function set as input to CallGraph
// instead of the whole program (i.e., ssautil.AllFunctions(prog)).
func TestVTAProgVsFuncSet(t *testing.T) {
	prog, want, err := testProg("testdata/src/callgraph_nested_ptr.go")
	if err != nil {
		t.Fatalf("couldn't load test `testdata/src/callgraph_nested_ptr.go`: %s", err)
	}
	if len(want) == 0 {
		t.Fatal("couldn't find want in `testdata/src/callgraph_nested_ptr.go`")
	}

	allFuncs := ssautil.AllFunctions(prog)
	g := CallGraph(allFuncs, cha.CallGraph(prog))
	// VTA over the whole program will produce a call graph that
	// includes Baz:(**i).Foo -> A.Foo, B.Foo.
	if got := callGraphStr(g); !subGraph(want, got) {
		t.Errorf("computed callgraph %v should contain %v", got, want)
	}

	// Prune the set of program functions to exclude Bar(). This should
	// yield a call graph that includes different set of callees for Baz
	// Baz:(**i).Foo -> A.Foo
	//
	// Note that the exclusion of Bar can happen, for instance, if Baz is
	// considered an entry point of some data flow analysis and Bar is
	// provably (e.g., using CHA forward reachability) unreachable from Baz.
	noBarFuncs := make(map[*ssa.Function]bool)
	for f, in := range allFuncs {
		noBarFuncs[f] = in && (funcName(f) != "Bar")
	}
	want = []string{"Baz: Do(i) -> Do; invoke t2.Foo() -> A.Foo"}
	g = CallGraph(noBarFuncs, cha.CallGraph(prog))
	if got := callGraphStr(g); !subGraph(want, got) {
		t.Errorf("pruned callgraph %v should contain %v", got, want)
	}
}

// TestVTAPanicMissingDefinitions tests if VTA gracefully handles the case
// where VTA panics when a definition of a function or method is not
// available, which can happen when using analysis package. A successful
// test simply does not panic.
func TestVTAPanicMissingDefinitions(t *testing.T) {
	run := func(pass *analysis.Pass) (interface{}, error) {
		s := pass.ResultOf[buildssa.Analyzer].(*buildssa.SSA)
		CallGraph(ssautil.AllFunctions(s.Pkg.Prog), cha.CallGraph(s.Pkg.Prog))
		return nil, nil
	}

	analyzer := &analysis.Analyzer{
		Name: "test",
		Doc:  "test",
		Run:  run,
		Requires: []*analysis.Analyzer{
			buildssa.Analyzer,
		},
	}

	testdata := analysistest.TestData()
	res := analysistest.Run(t, testdata, analyzer, "t", "d")
	if len(res) != 2 {
		t.Errorf("want analysis results for 2 packages; got %v", len(res))
	}
	for _, r := range res {
		if r.Err != nil {
			t.Errorf("want no error for package %v; got %v", r.Pass.Pkg.Path(), r.Err)
		}
	}
}