/*
** Copyright (c) 2007 D. Richard Hipp
**
** This program is free software; you can redistribute it and/or
** modify it under the terms of the GNU General Public
** License version 2 as published by the Free Software Foundation.
**
** 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 library; if not, write to the
** Free Software Foundation, Inc., 59 Temple Place - Suite 330,
** Boston, MA  02111-1307, USA.
**
** Author contact information:
**   drh@hwaci.com
**   http://www.hwaci.com/drh/
**
*******************************************************************************
**
** This file contains code used to merge the changes in the current
** checkout into a different version and switch to that version.
*/
#include "config.h"
#include "update.h"
#include <assert.h>

/*
** Return true if artifact rid is a version
*/
int is_a_version(int rid){
  return db_exists("SELECT 1 FROM plink WHERE cid=%d", rid);
}

/*
** COMMAND: update
**
** Usage: %fossil update ?VERSION?
**
** The optional argument is a version that should become the current
** version.  If the argument is omitted, then use the leaf of the
** tree that begins with the current version, if there is only a 
** single leaf.  
**
** This command is different from the "checkout" in that edits are
** not overwritten.  Edits are merged into the new version.
**
*/
void update_cmd(void){
  int vid;              /* Current version */
  int tid;              /* Target version - version we are changing to */
  Stmt q;

  if( g.argc!=3 && g.argc!=2 ){
    usage("?VERSION?");
  }
  db_must_be_within_tree();
  vid = db_lget_int("checkout", 0);
  if( vid==0 ){
    vid = 1;
  }
  if( db_exists("SELECT 1 FROM vmerge") ){
    fossil_fatal("cannot update an uncommitted merge");
  }
  if( g.argc==3 ){
    tid = name_to_rid(g.argv[2]);
    if( tid==0 ){
      fossil_fatal("not a version: %s", g.argv[2]);
    }
    if( !is_a_version(tid) ){
      fossil_fatal("not a version: %s", g.argv[2]);
    }
  }else{
    compute_leaves(vid);
    if( db_int(0, "SELECT count(*) FROM leaves")>1 ){
      db_prepare(&q, 
        "%s "
        "   AND event.objid IN leaves"
        " ORDER BY event.mtime DESC",
        timeline_query_for_tty()
      );
      print_timeline(&q, 100);
      db_finalize(&q);
      fossil_fatal("Multiple descendents");
    }
    tid = db_int(0, "SELECT rid FROM leaves"); 
  }

  db_begin_transaction();
  vfile_check_signature(vid);
  undo_begin();
  load_vfile_from_rid(tid);

  /*
  ** The record.fn field is used to match files against each other.  The
  ** FV table contains one row for each each unique filename in
  ** in the current checkout, the pivot, and the version being merged.
  */
  db_multi_exec(
    "DROP TABLE IF EXISTS fv;"
    "CREATE TEMP TABLE fv("
    "  fn TEXT PRIMARY KEY,"      /* The filename */
    "  idv INTEGER,"              /* VFILE entry for current version */
    "  idt INTEGER,"              /* VFILE entry for target version */
    "  chnged BOOLEAN,"           /* True if current version has been edited */
    "  ridv INTEGER,"             /* Record ID for current version */
    "  ridt INTEGER "             /* Record ID for target */
    ");"
    "INSERT OR IGNORE INTO fv"
    " SELECT pathname, 0, 0, 0, 0, 0 FROM vfile"
  );
  db_prepare(&q,
    "SELECT id, pathname, rid FROM vfile"
    " WHERE vid=%d", tid
  );
  while( db_step(&q)==SQLITE_ROW ){
    int id = db_column_int(&q, 0);
    const char *fn = db_column_text(&q, 1);
    int rid = db_column_int(&q, 2);
    db_multi_exec(
      "UPDATE fv SET idt=%d, ridt=%d WHERE fn=%Q",
      id, rid, fn
    );
  }
  db_finalize(&q);
  db_prepare(&q,
    "SELECT id, pathname, rid, chnged FROM vfile"
    " WHERE vid=%d", vid
  );
  while( db_step(&q)==SQLITE_ROW ){
    int id = db_column_int(&q, 0);
    const char *fn = db_column_text(&q, 1);
    int rid = db_column_int(&q, 2);
    int chnged = db_column_int(&q, 3);
    db_multi_exec(
      "UPDATE fv SET idv=%d, ridv=%d, chnged=%d WHERE fn=%Q",
      id, rid, chnged, fn
    );
  }
  db_finalize(&q);

  db_prepare(&q, 
    "SELECT fn, idv, ridv, idt, ridt, chnged FROM fv ORDER BY 1"
  );
  while( db_step(&q)==SQLITE_ROW ){
    const char *zName = db_column_text(&q, 0);
    int idv = db_column_int(&q, 1);
    int ridv = db_column_int(&q, 2);
    int idt = db_column_int(&q, 3);
    int ridt = db_column_int(&q, 4);
    int chnged = db_column_int(&q, 5);

    if( idv>0 && ridv==0 && idt>0 ){
      /* Conflict.  This file has been added to the current checkout
      ** but also exists in the target checkout.  Use the current version.
      */
      printf("CONFLICT %s\n", zName);
    }else if( idt>0 && idv==0 ){
      /* File added in the target. */
      printf("ADD %s\n", zName);
      undo_save(zName);
      vfile_to_disk(0, idt, 0);
    }else if( idt>0 && idv>0 && ridt!=ridv && chnged==0 ){
      /* The file is unedited.  Change it to the target version */
      printf("UPDATE %s\n", zName);
      undo_save(zName);
      vfile_to_disk(0, idt, 0);
    }else if( idt==0 && idv>0 ){
      if( chnged ){
        printf("CONFLICT %s\n", zName);
      }else{
        char *zFullPath;
        printf("REMOVE %s\n", zName);
        undo_save(zName);
        zFullPath = mprintf("%s/%s", g.zLocalRoot, zName);
        unlink(zFullPath);
        free(zFullPath);
      }
    }else if( idt>0 && idv>0 && ridt!=ridv && chnged ){
      /* Merge the changes in the current tree into the target version */
      Blob e, r, t, v;
      char *zFullPath;
      printf("MERGE %s\n", zName);
      undo_save(zName);
      zFullPath = mprintf("%s/%s", g.zLocalRoot, zName);
      content_get(ridt, &t);
      content_get(ridv, &v);
      blob_zero(&e);
      blob_read_from_file(&e, zFullPath);
      blob_merge(&v, &e, &t, &r);
      blob_write_to_file(&r, zFullPath);
      free(zFullPath);
      blob_reset(&v);
      blob_reset(&e);
      blob_reset(&t);
      blob_reset(&r);
    }
  }
  db_finalize(&q);
  
  /*
  ** Clean up the mid and pid VFILE entries.  Then commit the changes.
  */
  db_multi_exec("DELETE FROM vfile WHERE vid!=%d", tid);
  manifest_to_disk(tid);
  db_lset_int("checkout", tid);
  db_end_transaction(0);
}
