Fossil

int is_a_version(int rid){
  return db_exists("SELECT 1 FROM plink WHERE cid=%d", rid);
}

/*
** COMMAND: update
**
** Usage: %fossil update ?VERSION? ?FILES...?
**
** Change the version of the current checkout to VERSION.  Any uncommitted
** changes are retained and applied to the new checkout.
**
** The VERSION argument can be a specific version or tag or branch name.
** If the VERSION argument is omitted, then the leaf of the the subtree
** that begins at the current version is used, if there is only a single
** leaf.  VERSION can also be "current" to select the leaf of the current
** version or "latest" to select the most recent check-in.
**
** If one or more FILES are listed after the VERSION then only the
** named files are candidates to be updated.  If FILES is omitted, all
** files in the current checkout are subject to be updated.
**
** The -n or --nochange option causes this command to do a "dry run".  It
** prints out what would have happened but does not actually make any
** changes to the current checkout or the repository.
**
** The -v or --verbose option prints status information about unchanged
** files in addition to those file that actually do change.
*/
void update_cmd(void){
  int vid;              /* Current version */
  int tid=0;            /* Target version - version we are changing to */
  Stmt q;
  int latestFlag;       /* --latest.  Pick the latest version if true */
  int nochangeFlag;     /* -n or --nochange.  Do a dry run */
  int verboseFlag;      /* -v or --verbose.  Output extra information */

  url_proxy_options();
  latestFlag = find_option("latest",0, 0)!=0;
  nochangeFlag = find_option("nochange","n",0)!=0;
  verboseFlag = find_option("verbose","v",0)!=0;



  db_must_be_within_tree();
  vid = db_lget_int("checkout", 0);
  if( vid==0 ){
    fossil_fatal("cannot find current version");
  }
  if( db_exists("SELECT 1 FROM vmerge") ){
    fossil_fatal("cannot update an uncommitted merge");
  }

  if( g.argc>=3 ){
    if( strcmp(g.argv[2], "current")==0 ){
      /* If VERSION is "current", then use the same algorithm to find the
      ** target as if VERSION were omitted. */
    }else if( strcmp(g.argv[2], "latest")==0 ){
      /* If VERSION is "latest", then use the same algorithm to find the
      ** target as if VERSION were omitted and the --latest flag is present.
      */
      latestFlag = 1;
    }else{
      tid = name_to_rid(g.argv[2]);
      if( tid==0 ){
        fossil_fatal("no such version: %s", g.argv[2]);

      }else if( !is_a_version(tid) ){
        fossil_fatal("no such version: %s", g.argv[2]);
      }
    }
  }
  if( !nochangeFlag ) autosync(AUTOSYNC_PULL);
  
  if( tid==0 ){
    compute_leaves(vid, 1);
    if( !latestFlag && db_int(0, "SELECT count(*) FROM leaves")>1 ){

  ** 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 relative to root */
    "  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"

    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);

  /* If FILES appear on the command-line, remove from the "fv" table
  ** every entry that is not named on the command-line.
  */
  if( g.argc>=4 ){
    Blob sql;              /* SQL statement to purge unwanted entries */
    char *zSep = "(";      /* Separator in the list of filenames */
    Blob treename;         /* Normalized filename */
    int i;                 /* Loop counter */

    blob_zero(&sql);
    blob_append(&sql, "DELETE FROM fv WHERE fn NOT IN ", -1);
    for(i=3; i<g.argc; i++){
      file_tree_name(g.argv[i], &treename, 1);
      blob_appendf(&sql, "%s'%q'", zSep, blob_str(&treename));
      blob_reset(&treename);
      zSep = ",";
    }
    blob_append(&sql, ")", -1);
    db_multi_exec(blob_str(&sql));
    blob_reset(&sql);
  }

  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);  /* The filename from root */
    int idv = db_column_int(&q, 1);             /* VFILE entry for current */
    int ridv = db_column_int(&q, 2);            /* RecordID for current */
    int idt = db_column_int(&q, 3);             /* VFILE entry for target */
    int ridt = db_column_int(&q, 4);            /* RecordID for target */
    int chnged = db_column_int(&q, 5);          /* Current is edited */
    char *zFullPath;                            /* Full pathname of the file */

    zFullPath = mprintf("%s/%s", g.zLocalRoot, zName);
    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);
      if( !nochangeFlag ) 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);
      if( !nochangeFlag ) vfile_to_disk(0, idt, 0);
    }else if( idt>0 && idv>0 && file_size(zFullPath)<0 ){
      /* The file missing from the local check-out. Restore it to the
      ** version that appears in the target. */
      printf("UPDATE %s\n", zName);
      undo_save(zName);
      if( !nochangeFlag ) vfile_to_disk(0, idt, 0);
    }else if( idt==0 && idv>0 ){
      if( ridv==0 ){
        /* Added in current checkout.  Continue to hold the file as
        ** as an addition */
        db_multi_exec("UPDATE vfile SET vid=%d WHERE id=%d", tid, idv);
      }else if( chnged ){
        /* Edited locally but deleted from the target.  Delete it. */
        printf("CONFLICT %s\n", zName);
      }else{
        char *zFullPath;
        printf("REMOVE %s\n", zName);
        undo_save(zName);
        zFullPath = mprintf("%s/%s", g.zLocalRoot, zName);
        if( !nochangeFlag ) 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;
      int rc;

      printf("MERGE %s\n", zName);
      undo_save(zName);

      content_get(ridt, &t);
      content_get(ridv, &v);
      blob_zero(&e);
      blob_read_from_file(&e, zFullPath);
      rc = blob_merge(&v, &e, &t, &r);
      if( rc>=0 ){
        if( !nochangeFlag ) blob_write_to_file(&r, zFullPath);
        if( rc>0 ){
          printf("***** %d merge conflicts in %s\n", rc, zName);
        }
      }else{
        printf("***** Cannot merge binary file %s\n", zName);
      }

      blob_reset(&v);
      blob_reset(&e);
      blob_reset(&t);
      blob_reset(&r);
    }else if( verboseFlag ){
      printf("UNCHANGED %s\n", zName);
    }
    free(zFullPath);
  }
  db_finalize(&q);
  
  /*
  ** Clean up the mid and pid VFILE entries.  Then commit the changes.
  */
  if( nochangeFlag ){
    db_end_transaction(1);  /* With --nochange, rollback changes */
  }else{
    if( g.argc<=3 ){
      /* All files updated.  Shift the current checkout to the target. */
      db_multi_exec("DELETE FROM vfile WHERE vid!=%d", tid);
      manifest_to_disk(tid);
      db_lset_int("checkout", tid);
    }else{
      /* A subset of files have been checked out.  Keep the current
      ** checkout unchanged. */
      db_multi_exec("DELETE FROM vfile WHERE vid!=%d", vid);
    }
    db_end_transaction(0);
  }
}


/*
** Get the contents of a file within a given revision.