module Prick
  ### TIME

  EPOCH = Time.at(0).utc

  ### DIRECTORIES AND FILE NAMES

  # Shared files (part of the installation)
  SHARE_PATH = "#{File.dirname(File.dirname(__dir__))}/lib/share"
  LIBEXEC_PATH = "#{File.dirname(File.dirname(__dir__))}/lib/libexec"

  # Project directories
  DIRS = [
    MIGRATION_DIR = "migration",
    SCHEMA_DIR = "schema",
    SCHEMA_PRICK_DIR = "#{SCHEMA_DIR}/prick",
    PUBLIC_DIR = "#{SCHEMA_DIR}/public",
    BIN_DIR = "bin",
    LIBEXEC_DIR = "libexec",
    VAR_DIR = "var",
    CACHE_DIR = "#{VAR_DIR}/cache",
    SPOOL_DIR = "#{VAR_DIR}/spool",
    TMP_DIR = "tmp",
    CLONE_DIR = "tmp/clones",
    SPEC_DIR = "spec"
  ]

  # Prick project root directory
  PRICK_DIR = Dir.getwd

  # Search path for executables
  PRICK_PATH = "#{ENV['PATH']}:#{PRICK_DIR}/#{BIN_DIR}:#{PRICK_DIR}/#{LIBEXEC_DIR}"

  # Project specification file
  PRICK_PROJECT_FILE = "prick.yml"
  PRICK_PROJECT_PATH = PRICK_PROJECT_FILE

# # Environment specification file
# PRICK_ENVIRONMENT_FILE = "prick.environment.yml"
# PRICK_ENVIRONMENTS_PATH = PRICK_ENVIRONMENT_FILE

  # Context file
  PRICK_CONTEXT_FILE = ".prick-context"
  PRICK_CONTEXT_PATH = PRICK_CONTEXT_FILE

  # Fox state file (contains anchors and table sizes)
  FOX_STATE_FILE = ".fox-state.yml"
  FOX_STATE_PATH = FOX_STATE_FILE

  # Reflections file
  REFLECTIONS_FILE = "reflections.yml"
  REFLECTIONS_PATH = File.join(SCHEMA_DIR, REFLECTIONS_FILE)

  # Schema data file
  SCHEMA_VERSION_FILE = "data.sql"
  SCHEMA_VERSION_PATH = File.join(SCHEMA_PRICK_DIR, SCHEMA_VERSION_FILE)

  # Rspec temporary directory
  SPEC_TMP_DIR = "spec"
  SPEC_TMP_PATH = File.join(TMP_DIR, SPEC_TMP_DIR)


  # Migration diff files
  DIFF_FILE = "diff.sql"
  DIFF_FILES = [
    BEFORE_TABLES_DIFF_FILE = "diff.before-tables.sql",
    TABLES_DIFF_FILE = "diff.tables.sql",
    AFTER_TABLES_DIFF_FILE = "diff.after-tables.sql"
  ]




  # Not in use:

  # The project state file
  PROJECT_STATE_FILE = ".prick-project"
  PROJECT_STATE_PATH = PROJECT_STATE_FILE

  # The the .prick-migration file
  PRICK_MIGRATION_FILE = ".prick-migration"
  PRICK_MIGRATION_PATH = File.join(MIGRATION_DIR, PRICK_MIGRATION_FILE)

  # The the .prick-feature file
  PRICK_FEATURE_FILE = ".prick-feature"
  PRICK_FEATURE_PATH = File.join(MIGRATION_DIR, PRICK_FEATURE_FILE)

  # The strip-comments executable
  STRIP_COMMENTS_NAME = "strip-comments"
  STRIP_COMMENTS_PATH = File.join(LIBEXEC_PATH, "strip-comments")

  # Diff files
# DIFF_FILE = "diff.sql"
# BEFORE_TABLES_DIFF_NAME = "diff.before-tables.sql"
# TABLES_DIFF_NAME = "diff.tables.sql"
# AFTER_TABLES_DIFF_NAME = "diff.after-tables.sql"

# BEFORE_TABLES_DIFF_PATH = File.join(MIGRATION_DIR, BEFORE_TABLES_DIFF_NAME)
# TABLES_DIFF_PATH = File.join(MIGRATION_DIR, TABLES_DIFF_NAME)
# AFTER_TABLES_DIFF_PATH = File.join(MIGRATION_DIR, AFTER_TABLES_DIFF_NAME)
#
# TABLES_DIFF_SHARE_PATH = File.join(SHARE_PATH, "diff", TABLES_DIFF_NAME)


  # Dump files
  DUMP_EXT = "dump.gz"
  DUMP_GLOB = "*-[0-9]*.#{DUMP_EXT}"
  def self.dump_glob(project_name) "#{project_name}-*.#{DUMP_EXT}" end

  ### REGULAR EXPRESSIONS

  # Matches a system name. System names are used for objects that are external to prick
  # (like usernames)
  NAME_SUB_RE = /[a-z][a-z0-9_-]*/
  NAME_RE = /^#{NAME_SUB_RE}$/

  # Matches an identifier. Identifiers consist of lower case letters, digits
  # and underscores but not dashes because they're used as separators
  IDENT_SUB_RE = /[a-z][a-z0-9_]*/
  IDENT_RE = /^#{IDENT_SUB_RE}$/

  # Matches a project name
  PROJECT_NAME_SUB_RE = IDENT_SUB_RE
  PROJECT_NAME_RE = IDENT_RE

  # Matches a custom name
  CUSTOM_NAME_SUB_RE = IDENT_SUB_RE
  CUSTOM_NAME_RE = IDENT_RE

  # Matches a feature name
  FEATURE_NAME_SUB_RE = /(?!initial)#{IDENT_SUB_RE}/
  FEATURE_NAME_RE = /^#{FEATURE_NAME_SUB_RE}$/

  # Matches a postgres user name
  USER_NAME_SUB_RE = NAME_SUB_RE
  USER_NAME_RE = NAME_RE

  # Matches a major.minor.patch ('MMP') version
  #
  # The *_SEMVER REs are derived from the canonical RE 
  #
  # /
  #   (0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)
  #   (?:-((?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*)(?:\.(?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*))*))?
  #   (?:\+([0-9a-zA-Z-]+(?:\.[0-9a-zA-Z-]+)*))?
  # /x
  #
  # https://semver.org/#is-there-a-suggested-regular-expression-regex-to-check-a-semver-string.
  #
  MMP_SEMVER_SUB_RE = /(?:0|[1-9]\d*)\.(?:0|[1-9]\d*)\.(?:0|[1-9]\d*)/
  MMP_SEMVER_RE = /^#{MMP_SEMVER_SUB_RE}$/

  # Matches the prelease part of a semantic version
  #
  PRE_SEMVER_SUB_RE = /pre\.\d+/
  PRE_SEMVER_RE = /^#{PRE_SEMVER_SUB_RE}$/

  # Matches a semantic version
  #
  SEMVER_SUB_RE = /#{MMP_SEMVER_SUB_RE}(?:-#{PRE_SEMVER_SUB_RE})?/
  SEMVER_RE = /^#{SEMVER_SUB_RE}$/

  # Tag RE.  The general syntax for a tag is '<custom>-v<version>_<feature>'
  #
  # The RE defines the following captures:
  #   $1 - custom name, can be nil
  #   $2 - semantic version
  #   $3 - feature name, can be nil
  #
  TAG_SUB_RE = /
      (?:(#{CUSTOM_NAME_SUB_RE})-)?
      v
      (#{SEMVER_SUB_RE})
      (?:_(#{FEATURE_NAME_SUB_RE}))?
  /x
  TAG_RE = /^#{TAG_SUB_RE}$/

  # TODO: Handle initial branches (0.0.0-initial)

  # Branch RE. The general syntax for a branch is '<custom>-<version>_<feature>'
  #
  # The RE defines the following captures:
  #   $1 - custom name, can be nil
  #   $2 - semantic version
  #   $3 - feature name, can be nil
  #
  BRANCH_SUB_RE = /
      (?:(#{CUSTOM_NAME_SUB_RE})-)?
      (#{SEMVER_SUB_RE})
      (?:_(#{FEATURE_NAME_SUB_RE}))?
  /x
  BRANCH_RE = /^#{BRANCH_SUB_RE}$/

  # Tag or branch RE. The general syntax for a branch is '<custom>-v?<version>_<feature>'
  #
  # The RE defines the following captures:
  #   $1 - custom name, can be nil
  #   $2 - tag, nil or 'v'
  #   $3 - semantic version
  #   $4 - feature name, can be nil
  #
  VERSION_SUB_RE = /
      (?:(#{CUSTOM_NAME_SUB_RE})-)?
      (v)?
      (#{SEMVER_SUB_RE})
      (?:_(#{FEATURE_NAME_SUB_RE}))?
  /x
  VERSION_RE = /^#{VERSION_SUB_RE}$/

  # Matches an abstract release (either a release or a prerelease)
  #
  # The RE defines the following captures:
  #   $1 - custom name, can be nil
  #   $2 - semantic version
  #
  ABSTRACT_RELEASE_SUB_RE = /
      (?:(#{CUSTOM_NAME_SUB_RE})-)?
      (#{SEMVER_SUB_RE})
  /x
  ABSTRACT_RELEASE_RE = /^#{ABSTRACT_RELEASE_SUB_RE}$/

  # Project release RE. The general syntax is '<project>-<custom>-<version>'
  #
  # The RE defines the following captures:
  #   $1 - project
  #   $2 - version
  #   $3 - custom name, can be nil
  #   $4 - semantic version
  #
  PROJECT_SUB_RE = /(#{PROJECT_NAME_SUB_RE})-(#{ABSTRACT_RELEASE_SUB_RE})/
  PROJECT_RE = /^#{PROJECT_SUB_RE}$/
  def self.project_sub_re(project_name)
    /(#{Regexp.escape(project_name)})(-#{VERSION_SUB_RE})/
  end
  def self.release_re(project_name) /^#{project_sub_re(project_name)}$/ end

  # Matches versioned databases. Note that databases never include the feature name.
  # Features use the project database instead of a feature-specific database
  #
  # The RE defines the following captures
  #   $1 - project
  #   $2 - version
  #   $3 - custom name, can be nil
  #   $4 - semantic version
  #
  DATABASE_SUB_RE = PROJECT_SUB_RE
  DATABASE_RE = /^#{DATABASE_SUB_RE}$/
  def self.database_sub_re(project_name) project_sub_re(project_name) end
  def self.database_re(project_name) /^#{database_sub_re(project_name)}$/ end

  # Matches project database and versioned databases
  #
  # The RE defines the following captures
  #   $1 - project
  #   $2 - version, can be nil
  #   $3 - custom name, can be nil
  #   $4 - semantic version, can be nil
  #
  ALL_DATABASES_SUB_RE = /(#{PROJECT_NAME_SUB_RE})(?:-(#{ABSTRACT_RELEASE_SUB_RE}))?/
  ALL_DATABASES_RE = /^#{ALL_DATABASES_SUB_RE}$/
  def self.all_databases_sub_re(project_name) /(#{project_name})(?:-(#{ABSTRACT_RELEASE_SUB_RE}))?/ end
  def self.all_databases_re(project_name) /^#{all_databases_sub_re(project_name)}$/ end

  # Matches temporary databases. Mostly useful when debugging because temporary databases
  # should be deleted on exit
  TMP_DATABASES_SUB_RE = /#{PROJECT_NAME_SUB_RE}-(?:base|next)/
  TMP_DATABASES_RE = /^#{TMP_DATABASES_SUB_RE}$/
  def self.tmp_databases_sub_re(project_name) /#{project_name}-(?:base|next)/ end
  def self.tmp_databases_re(project_name) /^#{tmp_databases_sub_re(project_name)}$/ end
end