/*
Copyright 2016 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 jsonnet

import (
	"bytes"
	"encoding/json"
	"errors"
	"flag"
	"io/ioutil"
	"path/filepath"
	"strings"
	"testing"

	"github.com/google/go-jsonnet/ast"
	"github.com/sergi/go-diff/diffmatchpatch"
)

var update = flag.Bool("update", false, "update .golden files")

// TODO(sbarzowski) figure out how to measure coverage on the external tests

type testMetadata struct {
	extVars map[string]string
	extCode map[string]string
}

var standardExtVars = map[string]string{
	"stringVar": "2 + 2",
}

var standardExtCode = map[string]string{
	"codeVar":               "3 + 3",
	"errorVar":              "error 'xxx'",
	"staticErrorVar":        ")",
	"UndeclaredX":           "x",
	"selfRecursiveVar":      `[42, std.extVar("selfRecursiveVar")[0] + 1]`,
	"mutuallyRecursiveVar1": `[42, std.extVar("mutuallyRecursiveVar2")[0] + 1]`,
	"mutuallyRecursiveVar2": `[42, std.extVar("mutuallyRecursiveVar1")[0] + 1]`,
}

var metadataForTests = map[string]testMetadata{
	"testdata/extvar_code":               testMetadata{extVars: standardExtVars, extCode: standardExtCode},
	"testdata/extvar_error":              testMetadata{extVars: standardExtVars, extCode: standardExtCode},
	"testdata/extvar_hermetic":           testMetadata{extVars: standardExtVars, extCode: standardExtCode},
	"testdata/extvar_mutually_recursive": testMetadata{extVars: standardExtVars, extCode: standardExtCode},
	"testdata/extvar_self_recursive":     testMetadata{extVars: standardExtVars, extCode: standardExtCode},
	"testdata/extvar_static_error":       testMetadata{extVars: standardExtVars, extCode: standardExtCode},
	"testdata/extvar_string":             testMetadata{extVars: standardExtVars, extCode: standardExtCode},
}

type mainTest struct {
	name   string
	input  string
	golden string
	meta   *testMetadata
}

var jsonToString = &NativeFunction{
	Name:   "jsonToString",
	Params: ast.Identifiers{"x"},
	Func: func(x []interface{}) (interface{}, error) {
		bytes, err := json.Marshal(x[0])
		if err != nil {
			return nil, err
		}
		return string(bytes), nil
	},
}

var nativeError = &NativeFunction{
	Name: "nativeError",
	Params: ast.Identifiers{},
	Func: func(x []interface{}) (interface{}, error) {
		return nil, errors.New("Native function error")
	},
}

type jsonnetInput struct {
	name    string
	input   []byte
	eKind   evalKind
	extVars map[string]string
	extCode map[string]string
}

type jsonnetResult struct {
	output  string
	isError bool
}

func runJsonnet(i jsonnetInput) jsonnetResult {
	vm := MakeVM()
	errFormatter := termErrorFormatter{pretty: true, maxStackTraceSize: 9}

	for name, value := range i.extVars {
		vm.ExtVar(name, value)
	}
	for name, value := range i.extCode {
		vm.ExtCode(name, value)
	}

	vm.NativeFunction(jsonToString)
	vm.NativeFunction(nativeError)

	var output string

	rawOutput, err := vm.evaluateSnippet(i.name, string(i.input), i.eKind)
	var isError bool
	if err != nil {
		// TODO(sbarzowski) perhaps somehow mark that we are processing
		// an error. But for now we can treat them the same.
		output = errFormatter.Format(err)
		output += "\n"
		isError = true
	} else {
		output = rawOutput.(string)
		isError = false
	}

	return jsonnetResult{
		output:  output,
		isError: isError,
	}
}

func runTest(t *testing.T, test *mainTest) {

	read := func(file string) []byte {
		bytz, err := ioutil.ReadFile(file)
		if err != nil {
			t.Fatalf("reading file: %s: %v", file, err)
		}
		return bytz
	}

	input := read(test.input)

	result := runJsonnet(jsonnetInput{
		name:    test.name,
		input:   input,
		eKind:   evalKindRegular,
		extVars: test.meta.extVars,
		extCode: test.meta.extCode,
	})

	// TODO(sbarzowski) report which files were updated
	if *update {
		err := ioutil.WriteFile(test.golden, []byte(result.output), 0666)
		if err != nil {
			t.Errorf("error updating golden files: %v", err)
		}
		return
	}
	golden := read(test.golden)
	if bytes.Compare(golden, []byte(result.output)) != 0 {
		// TODO(sbarzowski) better reporting of differences in whitespace
		// missing newline issues can be very subtle now
		t.Fail()
		t.Errorf("Mismatch when running %s.jsonnet. Golden: %s\n", test.name, test.golden)
		data := diff(result.output, string(golden))
		t.Errorf("diff %s jsonnet %s.jsonnet\n", test.golden, test.name)
		t.Errorf(string(data))

	}
}

func TestMain(t *testing.T) {
	flag.Parse()
	var mainTests []mainTest
	match, err := filepath.Glob("testdata/*.jsonnet")
	if err != nil {
		t.Fatal(err)
	}

	for _, input := range match {
		golden := input
		name := input
		if strings.HasSuffix(input, ".jsonnet") {
			name = input[:len(input)-len(".jsonnet")]
			golden = name + ".golden"
		}
		var meta testMetadata
		if val, exists := metadataForTests[name]; exists {
			meta = val
		}
		mainTests = append(mainTests, mainTest{name: name, input: input, golden: golden, meta: &meta})
	}
	for _, test := range mainTests {
		t.Run(test.name, func(t *testing.T) {
			runTest(t, &test)
		})
	}
}

func diff(a, b string) string {
	dmp := diffmatchpatch.New()
	diffs := dmp.DiffMain(a, b, false)
	return dmp.DiffPrettyText(diffs)
}