require 'ostruct'
require 'yaml'
require 'cloud/settings'

# A Rack middleware application that creates a single configuration for Helix Web
# Services.
#
# Most web services are modular Sinatra applications, which does come with it's
# own settings mechanism. We should try to avoid those settings in most cases.
# Perhaps only if those settings are only relevant to the logic directly
# within the Sinatra app.
#
# Many other settings, like the port setting of the associated Helix Versioning
# Engine, should be exposed and overridable by the client application. These
# settings should be defined here.
#
# This class provides middleware that will inject an `hws_settings` object into
# each request. This `hws_settings` object is seeded by values declared on this
# class. When the system starts, our system config file is read in, and default
# system values are overridden. On any request, these settings can be
# overridden by the user.
#
# Additionally, there are "system" settings that are only overridable from the
# system config file. Client classes should reference this class directly:
# HWSSettings.system.
#
# ## Naming Conventions
#
# Use uppercase letters, numbers, or underscores only.
#
# ## HTTP Header Override Syntax
#
# We allow per-request overrides of settings via HTTP headers.
#
# The key format of the custom setting is:
#
# `X-PERFORCE-HELIX_WEB_SERVICES-{key}`
#
# For example:
#
#     X-PERFORCE-HELIX_WEB_SERVICES-P4HOST: perforce.mycompany.com
#     X-PERFORCE-HELIX_WEB_SERVICES-P4CHARSET: auto
#
# Please note that headers will be converted by Rack to all uppercase, hence
# our naming conventions.
#
# ## System Config File
#
# The system configuration is stored in the
# `/etc/perforce/helix_web_services.conf` file. This is a YAML
# file, and we override any locally defined variables with values found in
# this file. ()If you specify a value in this file we do not locally define,
# we ignore it.)
#
# Example values in /etc/perforce/helix_web_services.conf:
#
#     P4HOST: 'perforce.mycompany.com'
#     P4PORT: '9991'
#
#
class HWSSettings
  SYSTEM_CONFIG_PATH = ENV['HWS_CONFIG'] || '/etc/perforce/helix_web_services.conf'

  @settings = OpenStruct.new(
      # The .git-fusion depot name
      :GIT_FUSION_DEPOT => '.git-fusion',
      # If set, the HVEProjects class will use this path to locate projects
      # in the system.
      :HVE_PROJECTS_PATH => nil,
      # The current API level used to interact with the Perforce server
      :P4APILEVEL => '78',
      # The hostname of the p4d (Helix Versioning Engine) instance
      :P4HOST => nil,
      # The port of the p4d (Helix Versioning Engine) instance
      :P4PORT => '1666',
      # The charset setting to use when connecting to the p4d instance
      :P4CHARSET => 'auto',
      # The password or ticket to use when generating the p4 connection for the
      # method
      :P4PASSWD => nil
  )

  @system = OpenStruct.new(
      # Allow the indicated commands to be used in the
      # /p4/v1/commands methods
      # Each entry is either a string (the command name) or an Array of command
      # and required arguments.
      :COMMAND_WHITELIST => ['info', ['files', '-m']],
      # We'll load up any ruby scripts after initializing most of our code
      # here, in case rules need to be added.
      :CUSTOM_SCRIPTS => '/var/lib/perforce/helix_web_services/scripts',
      :DATA_DIR => '/var/lib/perforce/helix_web_services',
      # Enable Git Fusion project helpers.
      :ENABLE_GIT_FUSION => false,
      # If you receive a 'p4 trust' failure, this will accept the trust from
      # the remote server and retry again. This is not recommended for
      # production servers. You should use TRUST_FINGERPRINTS instead
      :ENABLE_MAN_IN_MIDDLE_ATTACKS => false,
      # If you should use HTTPS at the nginx level or not
      :ENABLE_HTTPS => true,
      # The amount of time the Helix Sync submit reconciliation mechanism will
      # retry any reconciliation failures.
      :HELIX_SYNC_RECONCILE_RETRIES => 5,
      :HELIX_SYNC_LOCK_RETRIES => 30,
      # The directory location we direct all logs to
      :LOG_DIR => '/var/log/perforce/helix_web_services',
      # Path to the 'nginx' executable
      :NGINX_COMMAND => '/opt/perforce/helix-web-services/embedded/sbin/nginx',
      # The nginx configuration is reset on restart
      :NGINX_CONFIG_PATH => '/var/run/perforce/helix_web_services/nginx.conf',
      :NGINX_WORKER_CONNECTIONS => 128,
      # What port nginx should respond to
      :NGINX_PORT => 443,
      # The local file to use for p4trust (if ENV['P4TRUST'] isn't set)
      :P4TRUST => '/var/lib/perforce/helix_web_services/p4trust',
      :RACKUP_CONFIG => '/opt/perforce/helix-web-services/embedded/service/helix_web_services/config.ru',
      :RUN_DIR => '/var/run/perforce/helix_web_services',
      :SSL_CERTIFICATE_PATH => '/opt/perforce/helix-web-services/nginx.crt',
      :SSL_CERTIFICATE_KEY_PATH => '/opt/perforce/helix-web-services/nginx.key',
      # If this is set, this is the file location where trusted fingerprints
      # are stored, one per line. We will *only* accept the fingerprint in
      # this file.
      :TRUST_FINGERPRINTS => nil,
      # The local file location that defines where services are located
      :SERVICE_CONFIGURATION => '/etc/perforce/services.json',
      # This is the user account we run unicorn as, which should be set during
      # the installation process.
      :SYSTEM_GROUP => 'helixwebservices',
      :SYSTEM_USER => 'helixwebservices',
      # Use this working directory for temporary workspaces (typically for making submits)
      :WORKSPACE_DIR => '/var/lib/perforce/helix_web_services/workspaces',
      :UNICORN_COMMAND => 'unicorn',
      :UNICORN_CONFIG_PATH => '/var/run/perforce/helix_web_services/unicorn.conf',
      # Unicorn will use this path to communicate to nginx.
      :UNICORN_CONNECTION => 'unix:/var/run/perforce/helix_web_services/unicorn.sock',
      # Seconds until we kill the unicorn process.
      # This is pretty slow (5 minutes) to let Helix Sync submit work
      :UNICORN_TIMEOUT => 300,
      # The number of forks we run.
      :UNICORN_WORKER_PROCESSES => 8
  )

  class << self

    # Returns baseline settings with system overrides applied.
    #
    # This is a copy of state. If you want to alter the default settings in
    # code instead of via config files, use the `settings_handle`
    def settings
      s = OpenStruct.new(@settings)
      s.each_pair do |key, _|
        if overrides.respond_to?(key)
          s[key] = overrides[key]
        end
      end
      s
    end

    # You can tweak the default settings directly here in code.
    def settings_handle
      @settings
    end

    # Returns our system settings overridden by local configuration in overrides.
    #
    # This is a *copy* of the class system settings, suitable for editing and
    # passing on.
    #
    # See the official guide for declared options.
    def system
      s = OpenStruct.new(@system)
      s.each_pair do |key, _|
        if overrides.respond_to?(key)
          s[key] = overrides[key]
        end
      end
      s
    end

    # In case your code wants to edit the system classes directly. Typically
    # used for test initialization.
    def system_handle
      @system
    end

    # Return the system overrides in our system configuration file.
    def overrides
      return @overrides ||= init_overrides
    end

    private

    def init_overrides
      system_conf_path = ENV['SYSTEM_CONFIG_PATH'] || SYSTEM_CONFIG_PATH
      if File.exists?(system_conf_path)
        yaml = YAML.load_file(SYSTEM_CONFIG_PATH)
        OpenStruct.new(yaml)
      end
    end

  end

  def initialize(app)
    @app = app
  end

  def call(env)
    hws_settings = self.class.settings

    # TODO: need to whitelist P4PORT for cloud, arbitrary perforce servers not supported
    env.each do |key, value|
      match = /^HTTP_X_PERFORCE_HELIX_WEB_SERVICES_(.*)$/.match(key)
      if match
        hws_settings[match[1]] = value
      end
    end

    env['hws_settings'] = hws_settings

    @app.call(env)
  end
end