require 'mkmf'

dir_config("dbm")

if dblib = with_config("dbm-type", nil)
  dblib = dblib.split(/[ ,]+/)
else
  dblib = %w(libc db db2 db1 db5 db4 db3 dbm gdbm gdbm_compat qdbm)
end

headers = {
  "libc" => ["ndbm.h"], # 4.4BSD libc contains Berkeley DB 1.
  "db" => ["db.h"],
  "db1" => ["db1/ndbm.h", "db1.h", "ndbm.h"],
  "db2" => ["db2/db.h", "db2.h", "db.h"],
  "db3" => ["db3/db.h", "db3.h", "db.h"],
  "db4" => ["db4/db.h", "db4.h", "db.h"],
  "db5" => ["db5/db.h", "db5.h", "db.h"],
  "dbm" => ["ndbm.h"], # traditional ndbm (4.3BSD)
  "gdbm" => ["gdbm-ndbm.h", "ndbm.h", "gdbm/ndbm.h"], # gdbm until 1.8.0
  "gdbm_compat" => ["gdbm-ndbm.h", "ndbm.h", "gdbm/ndbm.h"], # gdbm since 1.8.1
  "qdbm" => ["relic.h", "qdbm/relic.h"],
}

class << headers
  attr_accessor :found
  attr_accessor :defs
end
headers.found = []
headers.defs = nil

def headers.db_check(db, hdr)
  old_libs = $libs.dup
  old_defs = $defs.dup
  result = db_check2(db, hdr)
  if !result
    $libs = old_libs
    $defs = old_defs
  end
  result
end

def headers.db_check2(db, hdr)
  hsearch = nil

  case db
  when /^db[2-5]?$/
    hsearch = "-DDB_DBM_HSEARCH"
  when "gdbm_compat"
    have_library("gdbm") or return false
  end

  if (have_type("DBM", hdr, hsearch) || have_type("DBM", ["db.h", hdr], hsearch)) and
     (db == 'libc' ? have_func('dbm_open("", 0, 0)', hdr, hsearch) :
                     have_library(db, 'dbm_open("", 0, 0)', hdr, hsearch)) and
     have_func('dbm_clearerr((DBM *)0)', hdr, hsearch)
    if hsearch
      $defs << hsearch
      @defs = hsearch
    end
    $defs << '-DDBM_HDR="<'+hdr+'>"'
    @found << hdr
    true
  else
    false
  end
end

if dblib.any? {|db| headers.fetch(db, ["ndbm.h"]).any? {|hdr| headers.db_check(db, hdr) } }
  have_header("cdefs.h")
  have_header("sys/cdefs.h")
  have_func("dbm_pagfno((DBM *)0)", headers.found, headers.defs)
  have_func("dbm_dirfno((DBM *)0)", headers.found, headers.defs)
  convertible_int("datum.dsize", headers.found, headers.defs)
  create_makefile("dbm")
end