// Copyright 2018 The CUE Authors
//
// 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 cmd

import (
	"bytes"
	"io"
	"os"
	"strings"
	"testing"

	"cuelang.org/go/cue"
	"cuelang.org/go/cue/ast"
	"cuelang.org/go/cue/build"
	"cuelang.org/go/cue/errors"
	"cuelang.org/go/cue/load"
	"cuelang.org/go/cue/parser"
	"github.com/spf13/cobra"
	"golang.org/x/text/language"
	"golang.org/x/text/message"
)

// Disallow
// - block comments
// - old-style field comprehensions
const syntaxVersion = -1000 + 12

var defaultConfig = &load.Config{
	Context: build.NewContext(
		build.ParseFile(func(name string, src interface{}) (*ast.File, error) {
			return parser.ParseFile(name, src,
				parser.FromVersion(syntaxVersion),
				parser.ParseComments,
			)
		})),
}

var runtime = &cue.Runtime{}

var inTest = false

func mustParseFlags(t *testing.T, cmd *cobra.Command, flags ...string) {
	if err := cmd.ParseFlags(flags); err != nil {
		t.Fatal(err)
	}
}

func exitIfErr(cmd *Command, inst *cue.Instance, err error, fatal bool) {
	exitOnErr(cmd, err, fatal)
}

func getLang() language.Tag {
	loc := os.Getenv("LC_ALL")
	if loc == "" {
		loc = os.Getenv("LANG")
	}
	loc = strings.Split(loc, ".")[0]
	return language.Make(loc)
}

func exitOnErr(cmd *Command, err error, fatal bool) {
	if err == nil {
		return
	}

	// Link x/text as our localizer.
	p := message.NewPrinter(getLang())
	format := func(w io.Writer, format string, args ...interface{}) {
		p.Fprintf(w, format, args...)
	}

	cwd, _ := os.Getwd()

	w := &bytes.Buffer{}
	errors.Print(w, err, &errors.Config{
		Format:  format,
		Cwd:     cwd,
		ToSlash: inTest,
	})

	b := w.Bytes()
	_, _ = cmd.Stderr().Write(b)
	if fatal {
		exit()
	}
}

func buildFromArgs(cmd *Command, args []string) []*cue.Instance {
	binst := loadFromArgs(cmd, args, defaultConfig)
	if binst == nil {
		return nil
	}
	return buildInstances(cmd, binst)
}

func loadFromArgs(cmd *Command, args []string, cfg *load.Config) []*build.Instance {
	binst := load.Instances(args, cfg)
	if len(binst) == 0 {
		return nil
	}
	return binst
}

func buildInstances(cmd *Command, binst []*build.Instance) []*cue.Instance {
	// TODO:
	// If there are no files and User is true, then use those?
	// Always use all files in user mode?
	instances := cue.Build(binst)
	for _, inst := range instances {
		// TODO: consider merging errors of multiple files, but ensure
		// duplicates are removed.
		exitIfErr(cmd, inst, inst.Err, true)
	}

	if flagIgnore.Bool(cmd) {
		return instances
	}

	// TODO check errors after the fact in case of ignore.
	for _, inst := range instances {
		// TODO: consider merging errors of multiple files, but ensure
		// duplicates are removed.
		exitIfErr(cmd, inst, inst.Value().Validate(), !flagIgnore.Bool(cmd))
	}
	return instances
}

func buildToolInstances(cmd *Command, binst []*build.Instance) ([]*cue.Instance, error) {
	instances := cue.Build(binst)
	for _, inst := range instances {
		if inst.Err != nil {
			return nil, inst.Err
		}
	}

	// TODO check errors after the fact in case of ignore.
	for _, inst := range instances {
		if err := inst.Value().Validate(); err != nil {
			return nil, err
		}
	}
	return instances, nil
}

func buildTools(cmd *Command, args []string) (*cue.Instance, error) {
	binst := loadFromArgs(cmd, args, &load.Config{Tools: true})
	if len(binst) == 0 {
		return nil, nil
	}

	included := map[string]bool{}

	ti := binst[0].Context().NewInstance(binst[0].Root, nil)
	for _, inst := range binst {
		for _, f := range inst.ToolCUEFiles {
			if file := inst.Abs(f); !included[file] {
				_ = ti.AddFile(file, nil)
				included[file] = true
			}
		}
	}

	insts, err := buildToolInstances(cmd, binst)
	if err != nil {
		return nil, err
	}

	inst := cue.Merge(insts...).Build(ti)
	return inst, inst.Err
}