// Copyright 2018 The Fuchsia 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 cmdline

import (
	"encoding/json"
	"fidl/compiler/backend/types"
	"flag"
	"io/ioutil"
	"log"
)

// Flags common to all FIDL backends.
type Flags struct {
	jsonPath    *string
	outputBase  *string
	includeBase *string
}

// BaseFlags returns the common set of flags for FIDL backends.
func BaseFlags() Flags {
	return Flags{
		flag.String("json", "",
			"relative path to the FIDL intermediate representation."),
		flag.String("output-base", "",
			"the base file name for files generated by this generator."),
		flag.String("include-base", "",
			"the directory to which C and C++ includes should be relative."),
	}
}

// Valid returns true if the parsed flags are valid.
func (f Flags) Valid() bool {
	return *f.jsonPath != "" && *f.outputBase != "" && *f.includeBase != ""
}

// FidlTypes returns the root FIDL type information from the JSON file specified as an argument.
func (f Flags) FidlTypes() types.Root {
	bytes, err := ioutil.ReadFile(*f.jsonPath)
	if err != nil {
		log.Fatalf("Error reading from %s: %v", *f.jsonPath, err)
	}

	var fidl types.Root
	err = json.Unmarshal(bytes, &fidl)
	if err != nil {
		log.Fatalf("Error parsing JSON as FIDL data: %v", err)
	}

	for _, l := range fidl.Libraries {
		for k, v := range l.Decls {
			fidl.Decls[types.EnsureLibrary(l.Name, k)] = v
		}
	}

	return fidl
}

// Config returns the Config object for the supplied flags.
func (f Flags) Config() types.Config {
	return types.Config{
		OutputBase:  *f.outputBase,
		IncludeBase: *f.includeBase,
	}
}