(************************************************************************)
(* This file is part of SKS.  SKS is free software; you can
   redistribute it and/or modify it under the terms of the GNU General
   Public License as published by the Free Software Foundation; either
   version 2 of the License, or (at your option) any later version.

   This program is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
   USA *)
(***********************************************************************)

(** Executable: Builds up the key database from a multi-file database dump.
  This version works faster by virtue of not actually copying the keys out of
  the datbaase dump, and only storing the locations of those keys.
*)
module F(M:sig end) =
struct
  open StdLabels
  open MoreLabels
  open Printf
  open Arg
  open Common
  module Set = PSet.Set
  module Unix = UnixLabels
  open Packet

  let settings = {
    Keydb.withtxn = false;
    Keydb.cache_bytes = !Settings.cache_bytes;
    Keydb.pagesize = !Settings.pagesize;
    Keydb.dbdir = !Settings.dbdir;
    Keydb.dumpdir = !Settings.dumpdir;
  }

  module Keydb = Keydb.Unsafe

  let n = match !Settings.n with 0 -> 1 | x -> x
  let maxkeys = n * 15000 
  let dumpdir = !Settings.dumpdir

  let lsdir dir = 
    let dirhandle = Unix.opendir dir in
    let rec loop accum = match (try Some (Unix.readdir dirhandle)
				with End_of_file -> None)
    with
	Some fname -> loop (fname::accum)
      | None -> accum
    in
    loop []

  let rec list_mapi list ~f = 
    let rec loop list i ~f = 
      match list with
	  [] -> []
	| x::tl -> (f i x)::(loop tl (i + 1) ~f)
    in
    loop list 0 ~f

  let timestr sec = 
    sprintf "%.2f min" (sec /. 60.)
      
  (******************************************************)

  type 'a badoption = Bad | Good of 'a | Done

  (** get single md using nextkey function *)
  let get_keymd fnum nextkey = 
    match (try nextkey () 
	   with e -> 
	     perror "error parsing key in file %d: %s.  Skipping rest of file" 
	     fnum (Printexc.to_string e);
	     None
	  )
    with
      | Some (pos,key) -> 
	  begin
	    try
	      let ckey = Fixkey.canonicalize key in

	      if ckey = key then 
		(* no need to canonicalize key *)

		let offset = { Keydb.fnum = fnum; 
			       Keydb.pos = pos; 
			     } 
		in
		Good (Keydb.key_to_metadata_large_offset offset key)
	      else
		(* must use canonicalized version of key *)
		Good (Keydb.key_to_metadata ckey)
	    with
		Fixkey.Bad_key -> Bad
	  end
      | None -> 
	  Done

  let rec get_keymds_rec ~max fnum nextkey accum =
    if max = 0 
    then (accum,0)
    else
      match get_keymd fnum nextkey with
	| Done -> (accum,max)
	| Bad -> get_keymds_rec ~max fnum nextkey accum
	| Good md -> 
	    get_keymds_rec ~max:(max-1) fnum nextkey 
	    (md::accum)
	    

  (** Fetches a collection of no more than max keys.  Returns (keys,bool), with
    the second argument being true of there is more to read from the given
    file. *)
  let rec get_keymds ~max fnum nextkey = 
    get_keymds_rec ~max fnum nextkey []


  let inchan_to_nextkey inchan = 
    let cin = new Channel.sys_in_channel inchan in
    Key.pos_next_of_channel cin

  let rec get_keymds_list ~max nflist partial =
    match nflist with 
	[] -> (partial,[])
      | (fnum,nextkey)::tl -> 
	  if max = 0 then (partial,nflist)
	  else 
	    let (mds,remaining) = get_keymds ~max fnum nextkey in
	    flush stdout;
	    if remaining > 0 then (
	      (* file must be done with, so don't pass it on *)
	      get_keymds_list ~max:remaining tl (List.rev_append mds partial)
	    ) else (
	      (* file is not (necessarily) done, 
		 but we've got the key mds we need *)
	      (List.rev_append mds partial,nflist)
	    )

  let get_keymds_list ~max nflist = get_keymds_list ~max nflist []

  let dbtimer = MTimer.create ()
  let timer = MTimer.create ()
  let run () = 
    set_logfile ".fastbuild";

    if Sys.file_exists !Settings.dbdir then (
      perror "KeyDB directory already exists.  Exiting.";
      eprintf "KeyDB directory already exists.  Exiting.\n";
      exit (-1)
    );
    Unix.mkdir !Settings.dbdir 0o700;

    Keydb.open_dbs settings;
    Keydb.set_meta ~key:"filters" ~data:"yminsky.dedup"; 

    let filearray = Keydb.get_dump_filearray () in
    let nfarray = Array.mapi ~f:(fun i x -> (i,inchan_to_nextkey x))
		    filearray in
    let nflist = Array.to_list nfarray in

    perror "Loading %d keys at a time" maxkeys;

    protect 
      ~f:(fun () ->
	    let rec loop nflist = match nflist with 
		[] -> ()
	      | nflist -> 
		  MTimer.start timer;

		  perror "Loading metadata..."; flush stdout;
		  let (mds,nflist) = get_keymds_list ~max:maxkeys nflist in
		  perror "   %d keys loaded, %d files left" 
		    (List.length mds) (List.length nflist);
		  MTimer.start dbtimer; 
		  Keydb.add_mds mds;
		  MTimer.stop dbtimer;

		  MTimer.stop timer;
		  perror "   DB time:  %s.  Total time: %s." 
		    (timestr (MTimer.read dbtimer)) 
		    (timestr (MTimer.read timer)); 
		  flush stdout;
		  loop nflist
		    
	    in
	    loop nflist
	 )
      ~finally:(fun () -> Keydb.close_dbs ())

end