require "sqlite3/errors"

module SQLite3
  # This module is intended for inclusion solely by the Database class. It
  # defines convenience methods for the various pragmas supported by SQLite3.
  #
  # For a detailed description of these pragmas, see the SQLite3 documentation
  # at http://sqlite.org/pragma.html.
  module Pragmas
    # Returns +true+ or +false+ depending on the value of the named pragma.
    def get_boolean_pragma(name)
      get_first_value("PRAGMA #{name}") != 0
    end

    # Sets the given pragma to the given boolean value. The value itself
    # may be +true+ or +false+, or any other commonly used string or
    # integer that represents truth.
    def set_boolean_pragma(name, mode)
      case mode
      when String
        case mode.downcase
        when "on", "yes", "true", "y", "t" then mode = "'ON'"
        when "off", "no", "false", "n", "f" then mode = "'OFF'"
        else
          raise SQLite3::Exception, "unrecognized pragma parameter #{mode.inspect}"
        end
      when true, 1
        mode = "ON"
      when false, 0, nil
        mode = "OFF"
      else
        raise SQLite3::Exception, "unrecognized pragma parameter #{mode.inspect}"
      end

      execute("PRAGMA #{name}=#{mode}")
    end

    # Requests the given pragma (and parameters), and if the block is given,
    # each row of the result set will be yielded to it. Otherwise, the results
    # are returned as an array.
    def get_query_pragma(name, *params, &block) # :yields: row
      if params.empty?
        execute("PRAGMA #{name}", &block)
      else
        args = "'" + params.join("','") + "'"
        execute("PRAGMA #{name}( #{args} )", &block)
      end
    end

    # Return the value of the given pragma.
    def get_enum_pragma(name)
      get_first_value("PRAGMA #{name}")
    end

    # Set the value of the given pragma to +mode+. The +mode+ parameter must
    # conform to one of the values in the given +enum+ array. Each entry in
    # the array is another array comprised of elements in the enumeration that
    # have duplicate values. See #synchronous, #default_synchronous,
    # #temp_store, and #default_temp_store for usage examples.
    def set_enum_pragma(name, mode, enums)
      match = enums.find { |p| p.find { |i| i.to_s.downcase == mode.to_s.downcase } }
      unless match
        raise SQLite3::Exception, "unrecognized #{name} #{mode.inspect}"
      end
      execute("PRAGMA #{name}='#{match.first.upcase}'")
    end

    # Returns the value of the given pragma as an integer.
    def get_int_pragma(name)
      get_first_value("PRAGMA #{name}").to_i
    end

    # Set the value of the given pragma to the integer value of the +value+
    # parameter.
    def set_int_pragma(name, value)
      execute("PRAGMA #{name}=#{value.to_i}")
    end

    # The enumeration of valid synchronous modes.
    SYNCHRONOUS_MODES = [["full", 2], ["normal", 1], ["off", 0]]

    # The enumeration of valid temp store modes.
    TEMP_STORE_MODES = [["default", 0], ["file", 1], ["memory", 2]]

    # The enumeration of valid auto vacuum modes.
    AUTO_VACUUM_MODES = [["none", 0], ["full", 1], ["incremental", 2]]

    # The list of valid journaling modes.
    JOURNAL_MODES = [["delete"], ["truncate"], ["persist"], ["memory"],
      ["wal"], ["off"]]

    # The list of valid locking modes.
    LOCKING_MODES = [["normal"], ["exclusive"]]

    # The list of valid encodings.
    ENCODINGS = [["utf-8"], ["utf-16"], ["utf-16le"], ["utf-16be"]]

    # The list of valid WAL checkpoints.
    WAL_CHECKPOINTS = [["passive"], ["full"], ["restart"], ["truncate"]]

    def application_id
      get_int_pragma "application_id"
    end

    def application_id=(integer)
      set_int_pragma "application_id", integer
    end

    def auto_vacuum
      get_enum_pragma "auto_vacuum"
    end

    def auto_vacuum=(mode)
      set_enum_pragma "auto_vacuum", mode, AUTO_VACUUM_MODES
    end

    def automatic_index
      get_boolean_pragma "automatic_index"
    end

    def automatic_index=(mode)
      set_boolean_pragma "automatic_index", mode
    end

    def busy_timeout
      get_int_pragma "busy_timeout"
    end

    def busy_timeout=(milliseconds)
      set_int_pragma "busy_timeout", milliseconds
    end

    def cache_size
      get_int_pragma "cache_size"
    end

    def cache_size=(size)
      set_int_pragma "cache_size", size
    end

    def cache_spill
      get_boolean_pragma "cache_spill"
    end

    def cache_spill=(mode)
      set_boolean_pragma "cache_spill", mode
    end

    def case_sensitive_like=(mode)
      set_boolean_pragma "case_sensitive_like", mode
    end

    def cell_size_check
      get_boolean_pragma "cell_size_check"
    end

    def cell_size_check=(mode)
      set_boolean_pragma "cell_size_check", mode
    end

    def checkpoint_fullfsync
      get_boolean_pragma "checkpoint_fullfsync"
    end

    def checkpoint_fullfsync=(mode)
      set_boolean_pragma "checkpoint_fullfsync", mode
    end

    def collation_list(&block) # :yields: row
      get_query_pragma "collation_list", &block
    end

    def compile_options(&block) # :yields: row
      get_query_pragma "compile_options", &block
    end

    def count_changes
      get_boolean_pragma "count_changes"
    end

    def count_changes=(mode)
      set_boolean_pragma "count_changes", mode
    end

    def data_version
      get_int_pragma "data_version"
    end

    def database_list(&block) # :yields: row
      get_query_pragma "database_list", &block
    end

    def default_cache_size
      get_int_pragma "default_cache_size"
    end

    def default_cache_size=(size)
      set_int_pragma "default_cache_size", size
    end

    def default_synchronous
      get_enum_pragma "default_synchronous"
    end

    def default_synchronous=(mode)
      set_enum_pragma "default_synchronous", mode, SYNCHRONOUS_MODES
    end

    def default_temp_store
      get_enum_pragma "default_temp_store"
    end

    def default_temp_store=(mode)
      set_enum_pragma "default_temp_store", mode, TEMP_STORE_MODES
    end

    def defer_foreign_keys
      get_boolean_pragma "defer_foreign_keys"
    end

    def defer_foreign_keys=(mode)
      set_boolean_pragma "defer_foreign_keys", mode
    end

    def encoding
      get_enum_pragma "encoding"
    end

    def encoding=(mode)
      set_enum_pragma "encoding", mode, ENCODINGS
    end

    def foreign_key_check(*table, &block) # :yields: row
      get_query_pragma "foreign_key_check", *table, &block
    end

    def foreign_key_list(table, &block) # :yields: row
      get_query_pragma "foreign_key_list", table, &block
    end

    def foreign_keys
      get_boolean_pragma "foreign_keys"
    end

    def foreign_keys=(mode)
      set_boolean_pragma "foreign_keys", mode
    end

    def freelist_count
      get_int_pragma "freelist_count"
    end

    def full_column_names
      get_boolean_pragma "full_column_names"
    end

    def full_column_names=(mode)
      set_boolean_pragma "full_column_names", mode
    end

    def fullfsync
      get_boolean_pragma "fullfsync"
    end

    def fullfsync=(mode)
      set_boolean_pragma "fullfsync", mode
    end

    def ignore_check_constraints=(mode)
      set_boolean_pragma "ignore_check_constraints", mode
    end

    def incremental_vacuum(pages, &block) # :yields: row
      get_query_pragma "incremental_vacuum", pages, &block
    end

    def index_info(index, &block) # :yields: row
      get_query_pragma "index_info", index, &block
    end

    def index_list(table, &block) # :yields: row
      get_query_pragma "index_list", table, &block
    end

    def index_xinfo(index, &block) # :yields: row
      get_query_pragma "index_xinfo", index, &block
    end

    def integrity_check(*num_errors, &block) # :yields: row
      get_query_pragma "integrity_check", *num_errors, &block
    end

    def journal_mode
      get_enum_pragma "journal_mode"
    end

    def journal_mode=(mode)
      set_enum_pragma "journal_mode", mode, JOURNAL_MODES
    end

    def journal_size_limit
      get_int_pragma "journal_size_limit"
    end

    def journal_size_limit=(size)
      set_int_pragma "journal_size_limit", size
    end

    def legacy_file_format
      get_boolean_pragma "legacy_file_format"
    end

    def legacy_file_format=(mode)
      set_boolean_pragma "legacy_file_format", mode
    end

    def locking_mode
      get_enum_pragma "locking_mode"
    end

    def locking_mode=(mode)
      set_enum_pragma "locking_mode", mode, LOCKING_MODES
    end

    def max_page_count
      get_int_pragma "max_page_count"
    end

    def max_page_count=(size)
      set_int_pragma "max_page_count", size
    end

    def mmap_size
      get_int_pragma "mmap_size"
    end

    def mmap_size=(size)
      set_int_pragma "mmap_size", size
    end

    # Attempt to optimize the database.
    #
    # To customize the optimization options, pass +bitmask+ with a combination
    # of the Constants::Optimize masks.
    #
    # See https://www.sqlite.org/pragma.html#pragma_optimize for more information.
    def optimize(bitmask = nil)
      if bitmask
        set_int_pragma "optimize", bitmask
      else
        execute("PRAGMA optimize")
      end
    end

    def page_count
      get_int_pragma "page_count"
    end

    def page_size
      get_int_pragma "page_size"
    end

    def page_size=(size)
      set_int_pragma "page_size", size
    end

    def parser_trace=(mode)
      set_boolean_pragma "parser_trace", mode
    end

    def query_only
      get_boolean_pragma "query_only"
    end

    def query_only=(mode)
      set_boolean_pragma "query_only", mode
    end

    def quick_check(*num_errors, &block) # :yields: row
      get_query_pragma "quick_check", *num_errors, &block
    end

    def read_uncommitted
      get_boolean_pragma "read_uncommitted"
    end

    def read_uncommitted=(mode)
      set_boolean_pragma "read_uncommitted", mode
    end

    def recursive_triggers
      get_boolean_pragma "recursive_triggers"
    end

    def recursive_triggers=(mode)
      set_boolean_pragma "recursive_triggers", mode
    end

    def reverse_unordered_selects
      get_boolean_pragma "reverse_unordered_selects"
    end

    def reverse_unordered_selects=(mode)
      set_boolean_pragma "reverse_unordered_selects", mode
    end

    def schema_cookie
      get_int_pragma "schema_cookie"
    end

    def schema_cookie=(cookie)
      set_int_pragma "schema_cookie", cookie
    end

    def schema_version
      get_int_pragma "schema_version"
    end

    def schema_version=(version)
      set_int_pragma "schema_version", version
    end

    def secure_delete
      get_boolean_pragma "secure_delete"
    end

    def secure_delete=(mode)
      set_boolean_pragma "secure_delete", mode
    end

    def short_column_names
      get_boolean_pragma "short_column_names"
    end

    def short_column_names=(mode)
      set_boolean_pragma "short_column_names", mode
    end

    def shrink_memory
      execute("PRAGMA shrink_memory")
    end

    def soft_heap_limit
      get_int_pragma "soft_heap_limit"
    end

    def soft_heap_limit=(mode)
      set_int_pragma "soft_heap_limit", mode
    end

    def stats(&block) # :yields: row
      get_query_pragma "stats", &block
    end

    def synchronous
      get_enum_pragma "synchronous"
    end

    def synchronous=(mode)
      set_enum_pragma "synchronous", mode, SYNCHRONOUS_MODES
    end

    def temp_store
      get_enum_pragma "temp_store"
    end

    def temp_store=(mode)
      set_enum_pragma "temp_store", mode, TEMP_STORE_MODES
    end

    def threads
      get_int_pragma "threads"
    end

    def threads=(count)
      set_int_pragma "threads", count
    end

    def user_cookie
      get_int_pragma "user_cookie"
    end

    def user_cookie=(cookie)
      set_int_pragma "user_cookie", cookie
    end

    def user_version
      get_int_pragma "user_version"
    end

    def user_version=(version)
      set_int_pragma "user_version", version
    end

    def vdbe_addoptrace=(mode)
      set_boolean_pragma "vdbe_addoptrace", mode
    end

    def vdbe_debug=(mode)
      set_boolean_pragma "vdbe_debug", mode
    end

    def vdbe_listing=(mode)
      set_boolean_pragma "vdbe_listing", mode
    end

    def vdbe_trace
      get_boolean_pragma "vdbe_trace"
    end

    def vdbe_trace=(mode)
      set_boolean_pragma "vdbe_trace", mode
    end

    def wal_autocheckpoint
      get_int_pragma "wal_autocheckpoint"
    end

    def wal_autocheckpoint=(mode)
      set_int_pragma "wal_autocheckpoint", mode
    end

    def wal_checkpoint
      get_enum_pragma "wal_checkpoint"
    end

    def wal_checkpoint=(mode)
      set_enum_pragma "wal_checkpoint", mode, WAL_CHECKPOINTS
    end

    def writable_schema=(mode)
      set_boolean_pragma "writable_schema", mode
    end

    ###
    # Returns information about +table+.  Yields each row of table information
    # if a block is provided.
    def table_info table
      stmt = prepare "PRAGMA table_info(#{table})"
      columns = stmt.columns

      needs_tweak_default =
        version_compare(SQLite3.libversion.to_s, "3.3.7") > 0

      result = [] unless block_given?
      stmt.each do |row|
        new_row = columns.zip(row).to_h

        tweak_default(new_row) if needs_tweak_default

        # Ensure the type value is downcased.  On Mac and Windows
        # platforms this value is now being returned as all upper
        # case.
        if new_row["type"]
          new_row["type"] = new_row["type"].downcase
        end

        if block_given?
          yield new_row
        else
          result << new_row
        end
      end
      stmt.close

      result
    end

    private

    # Compares two version strings
    def version_compare(v1, v2)
      v1 = v1.split(".").map { |i| i.to_i }
      v2 = v2.split(".").map { |i| i.to_i }
      parts = [v1.length, v2.length].max
      v1.push 0 while v1.length < parts
      v2.push 0 while v2.length < parts
      v1.zip(v2).each do |a, b|
        return -1 if a < b
        return 1 if a > b
      end
      0
    end

    # Since SQLite 3.3.8, the table_info pragma has returned the default
    # value of the row as a quoted SQL value. This method essentially
    # unquotes those values.
    def tweak_default(hash)
      case hash["dflt_value"]
      when /^null$/i
        hash["dflt_value"] = nil
      when /^'(.*)'$/m
        hash["dflt_value"] = $1.gsub("''", "'")
      when /^"(.*)"$/m
        hash["dflt_value"] = $1.gsub('""', '"')
      end
    end
  end
end