#!/usr/bin/env python
#
# Copyright 2014 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""
Utilities for the modular DevTools build.
"""

from os import path
import os

try:
    import simplejson as json
except ImportError:
    import json


def read_file(filename):
    with open(path.normpath(filename), 'rt') as input:
        return input.read()


def write_file(filename, content):
    if path.exists(filename):
        os.remove(filename)
    with open(filename, 'wt') as output:
        output.write(content)


def bail_error(message):
    raise Exception(message)


def load_and_parse_json(filename):
    try:
        return json.loads(read_file(filename))
    except:
        print 'ERROR: Failed to parse %s' % filename
        raise


def concatenate_scripts(file_names, module_dir, output_dir, output):
    for file_name in file_names:
        output.write('/* %s */\n' % file_name)
        file_path = path.join(module_dir, file_name)
        if not path.isfile(file_path):
            file_path = path.join(output_dir, path.basename(module_dir), file_name)
        output.write(read_file(file_path))
        output.write(';')


class Descriptors:
    def __init__(self, application_dir, application_descriptor, module_descriptors):
        self.application_dir = application_dir
        self.application = application_descriptor
        self.modules = module_descriptors
        self._cached_sorted_modules = None

    def application_json(self):
        return json.dumps(self.application.values())

    def all_compiled_files(self):
        files = {}
        for name in self.modules:
            module = self.modules[name]
            skipped_files = set(module.get('skip_compilation', []))
            for script in module.get('scripts', []):
                if script not in skipped_files:
                    files[path.normpath(path.join(self.application_dir, name, script))] = True
        return files.keys()

    def module_compiled_files(self, name):
        files = []
        module = self.modules.get(name)
        skipped_files = set(module.get('skip_compilation', []))
        for script in module.get('scripts', []):
            if script not in skipped_files:
                files.append(script)
        return files

    def module_resources(self, name):
        return [name + '/' + resource for resource in self.modules[name].get('resources', [])]

    def sorted_modules(self):
        if self._cached_sorted_modules:
            return self._cached_sorted_modules

        result = []
        unvisited_modules = set(self.modules)
        temp_modules = set()

        def visit(parent, name):
            if name not in unvisited_modules:
                return None
            if name not in self.modules:
                return (parent, name)
            if name in temp_modules:
                bail_error('Dependency cycle found at module "%s"' % name)
            temp_modules.add(name)
            deps = self.modules[name].get('dependencies')
            if deps:
                for dep_name in deps:
                    bad_dep = visit(name, dep_name)
                    if bad_dep:
                        return bad_dep
            unvisited_modules.remove(name)
            temp_modules.remove(name)
            result.append(name)
            return None

        while len(unvisited_modules):
            for next in unvisited_modules:
                break
            failure = visit(None, next)
            if failure:
                # failure[0] can never be None
                bail_error('Unknown module "%s" encountered in dependencies of "%s"' % (failure[1], failure[0]))

        self._cached_sorted_modules = result
        return result

    def sorted_dependencies_closure(self, module_name):
        visited = set()

        def sorted_deps_for_module(name):
            result = []
            desc = self.modules[name]
            deps = desc.get('dependencies', [])
            for dep in deps:
                result += sorted_deps_for_module(dep)
            if name not in visited:
                result.append(name)
                visited.add(name)
            return result

        return sorted_deps_for_module(module_name)


class DescriptorLoader:
    def __init__(self, application_dir):
        self.application_dir = application_dir

    def load_application(self, application_descriptor_name):
        return self.load_applications([application_descriptor_name])

    def load_applications(self, application_descriptor_names):
        merged_application_descriptor = {}
        all_module_descriptors = {}
        for application_descriptor_name in application_descriptor_names:
            module_descriptors = {}
            application_descriptor_filename = path.join(self.application_dir, application_descriptor_name)
            application_descriptor = {desc['name']: desc for desc in load_and_parse_json(application_descriptor_filename)}

            for name in application_descriptor:
                merged_application_descriptor[name] = application_descriptor[name]

            for (module_name, module) in application_descriptor.items():
                if module_descriptors.get(module_name):
                    bail_error('Duplicate definition of module "%s" in %s' % (module_name, application_descriptor_filename))
                if not all_module_descriptors.get(module_name):
                    module_descriptors[module_name] = self._read_module_descriptor(module_name, application_descriptor_filename)
                    all_module_descriptors[module_name] = module_descriptors[module_name]

            for module in module_descriptors.values():
                deps = module.get('dependencies', [])
                for dep in deps:
                    if dep not in application_descriptor:
                        bail_error('Module "%s" (dependency of "%s") not listed in application descriptor %s' % (dep, module['name'], application_descriptor_filename))

        return Descriptors(self.application_dir, merged_application_descriptor, all_module_descriptors)

    def _read_module_descriptor(self, module_name, application_descriptor_filename):
        json_filename = path.join(self.application_dir, module_name, 'module.json')
        if not path.exists(json_filename):
            bail_error('Module descriptor %s referenced in %s is missing' % (json_filename, application_descriptor_filename))
        module_json = load_and_parse_json(json_filename)
        module_json['name'] = module_name
        return module_json