/*
** Copyright (c) 2007 D. Richard Hipp
**
** This program is free software; you can redistribute it and/or
** modify it under the terms of the Simplified BSD License (also
** known as the "2-Clause License" or "FreeBSD License".)

** 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.
**
** Author contact information:
**   drh@hwaci.com
**   http://www.hwaci.com/drh/
**
*******************************************************************************
**
** This file contains code used to merge two or more branches into
** a single tree.
*/
#include "config.h"
#include "merge.h"
#include <assert.h>


/*
** COMMAND: merge
**
** Usage: %fossil merge [--cherrypick] [--backout] VERSION
**
** The argument VERSION is a version that should be merged into the
** current checkout.  All changes from VERSION back to the nearest
** common ancestor are merged.  Except, if either of the --cherrypick or
** --backout options are used only the changes associated with the
** single check-in VERSION are merged.  The --backout option causes
** the changes associated with VERSION to be removed from the current
** checkout rather than added.
**
** Only file content is merged.  The result continues to use the
** file and directory names from the current checkout even if those
** names might have been changed in the branch being merged in.
**
** Other options:
**
**   --baseline BASELINE     Use BASELINE as the "pivot" of the merge instead
**                           of the nearest common ancestor.  This allows
**                           a sequence of changes in a branch to be merged
**                           without having to merge the entire branch.
**
**   --detail                Show additional details of the merge
**
**   --binary GLOBPATTERN    Treat files that match GLOBPATTERN as binary
**                           and do not try to merge parallel changes.  This
**                           option overrides the "binary-glob" setting.
**
**   --nochange | -n         Dryrun:  do not actually make any changes; just
**                           show what would have happened.
*/
void merge_cmd(void){
  int vid;              /* Current version "V" */
  int mid;              /* Version we are merging from "M" */
  int pid;              /* The pivot version - most recent common ancestor P */
  int detailFlag;       /* True if the --detail option is present */
  int pickFlag;         /* True if the --cherrypick option is present */
  int backoutFlag;      /* True if the --backout option is present */
  int nochangeFlag;     /* True if the --nochange or -n option is present */
  const char *zBinGlob; /* The value of --binary */
  const char *zPivot;   /* The value of --baseline */
  int debugFlag;        /* True if --debug is present */
  int nChng;            /* Number of file name changes */
  int *aChng;           /* An array of file name changes */
  int i;                /* Loop counter */
  int nConflict = 0;    /* Number of conflicts seen */
  Stmt q;


  /* Notation:
  **
  **      V     The current checkout
  **      M     The version being merged in
  **      P     The "pivot" - the most recent common ancestor of V and M.
  */

  undo_capture_command_line();
  detailFlag = find_option("detail",0,0)!=0;
  pickFlag = find_option("cherrypick",0,0)!=0;
  backoutFlag = find_option("backout",0,0)!=0;
  debugFlag = find_option("debug",0,0)!=0;
  zBinGlob = find_option("binary",0,1);
  nochangeFlag = find_option("nochange","n",0)!=0;
  zPivot = find_option("baseline",0,1);
  if( g.argc!=3 ){
    usage("VERSION");
  }
  db_must_be_within_tree();
  if( zBinGlob==0 ) zBinGlob = db_get("binary-glob",0);
  vid = db_lget_int("checkout", 0);
  if( vid==0 ){
    fossil_fatal("nothing is checked out");
  }
  mid = name_to_typed_rid(g.argv[2], "ci");
  if( mid==0 || !is_a_version(mid) ){
    fossil_fatal("not a version: %s", g.argv[2]);
  }
  if( zPivot ){
    pid = name_to_typed_rid(zPivot, "ci");
    if( pid==0 || !is_a_version(pid) ){
      fossil_fatal("not a version: %s", zPivot);
    }
    if( pickFlag ){
      fossil_fatal("incompatible options: --cherrypick & --baseline");
    }
    /* pickFlag = 1;  // Using --baseline is really like doing a cherrypick */
  }else if( pickFlag || backoutFlag ){
    pid = db_int(0, "SELECT pid FROM plink WHERE cid=%d AND isprim", mid);
    if( pid<=0 ){
      fossil_fatal("cannot find an ancestor for %s", g.argv[2]);
    }
  }else{
    pivot_set_primary(mid);
    pivot_set_secondary(vid);
    db_prepare(&q, "SELECT merge FROM vmerge WHERE id=0");
    while( db_step(&q)==SQLITE_ROW ){
      pivot_set_secondary(db_column_int(&q,0));
    }
    db_finalize(&q);
    pid = pivot_find();
    if( pid<=0 ){
      fossil_fatal("cannot find a common ancestor between the current "
                   "checkout and %s", g.argv[2]);
    }
  }
  if( backoutFlag ){
    int t = pid;
    pid = mid;
    mid = t;
  }
  if( !is_a_version(pid) ){
    fossil_fatal("not a version: record #%d", pid);
  }
  vfile_check_signature(vid, 1, 0);
  db_begin_transaction();
  if( !nochangeFlag ) undo_begin();
  load_vfile_from_rid(mid);
  load_vfile_from_rid(pid);

  /*
  ** The vfile.pathname 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 */
    "  idp INTEGER,"              /* VFILE entry for the pivot */
    "  idm INTEGER,"              /* VFILE entry for version merging in */
    "  chnged BOOLEAN,"           /* True if current version has been edited */
    "  ridv INTEGER,"             /* Record ID for current version */
    "  ridp INTEGER,"             /* Record ID for pivot */
    "  ridm INTEGER,"             /* Record ID for merge */
    "  isexe BOOLEAN,"            /* Execute permission enabled */
    "  fnp TEXT,"                 /* The filename in the pivot */
    "  fnm TEXT"                  /* the filename in the merged version */
    ");"
  );

  /* Add files found in V
  */
  db_multi_exec(
    "INSERT OR IGNORE"
    " INTO fv(fn,fnp,fnm,idv,idp,idm,ridv,ridp,ridm,isexe,chnged)"
    " SELECT pathname, pathname, pathname, id, 0, 0, rid, 0, 0, isexe, chnged "
    " FROM vfile WHERE vid=%d",
    vid
  );

  /*
  ** Compute name changes from P->V
  */
  find_filename_changes(vid, pid, &nChng, &aChng);
  if( nChng ){
    for(i=0; i<nChng; i++){
      char *z;
      z = db_text(0, "SELECT name FROM filename WHERE fnid=%d", aChng[i*2+1]);
      db_multi_exec(
        "UPDATE fv SET fnp=%Q, fnm=%Q"
        " WHERE fn=(SELECT name FROM filename WHERE fnid=%d)",
        z, z, aChng[i*2]
      );
      free(z);
    }
    fossil_free(aChng);
    db_multi_exec("UPDATE fv SET fnm=fnp WHERE fnp!=fn");
  }

  /* Add files found in P but not in V
  */
  db_multi_exec(
    "INSERT OR IGNORE"
    " INTO fv(fn,fnp,fnm,idv,idp,idm,ridv,ridp,ridm,isexe,chnged)"
    " SELECT pathname, pathname, pathname, 0, 0, 0, 0, 0, 0, isexe, 0 "
    "   FROM vfile"
    "  WHERE vid=%d AND pathname NOT IN (SELECT fnp FROM fv)",
    pid
  );

  /*
  ** Compute name changes from P->M
  */
  find_filename_changes(pid, mid, &nChng, &aChng);
  if( nChng ){
    if( nChng>4 ) db_multi_exec("CREATE INDEX fv_fnp ON fv(fnp)");
    for(i=0; i<nChng; i++){
      db_multi_exec(
        "UPDATE fv SET fnm=(SELECT name FROM filename WHERE fnid=%d)"
        " WHERE fnp=(SELECT name FROM filename WHERE fnid=%d)",
        aChng[i*2+1], aChng[i*2]
      );
    }
    fossil_free(aChng);
  }

  /* Add files found in M but not in P or V.
  */
  db_multi_exec(
    "INSERT OR IGNORE"
    " INTO fv(fn,fnp,fnm,idv,idp,idm,ridv,ridp,ridm,isexe,chnged)"
    " SELECT pathname, pathname, pathname, 0, 0, 0, 0, 0, 0, isexe, 0 "
    "   FROM vfile"
    "  WHERE vid=%d"
    "    AND pathname NOT IN (SELECT fnp FROM fv UNION SELECT fnm FROM fv)",
    mid
  );

  /*
  ** Compute the file version ids for P and M.
  */
  db_multi_exec(
    "UPDATE fv SET"
    " idp=coalesce((SELECT id FROM vfile WHERE vid=%d AND pathname=fnp),0),"
    " ridp=coalesce((SELECT rid FROM vfile WHERE vid=%d AND pathname=fnp),0),"
    " idm=coalesce((SELECT id FROM vfile WHERE vid=%d AND pathname=fnm),0),"
    " ridm=coalesce((SELECT rid FROM vfile WHERE vid=%d AND pathname=fnm),0)",
    pid, pid, mid, mid
  );

  if( debugFlag ){
    db_prepare(&q,
       "SELECT rowid, fn, fnp, fnm, chnged, ridv, ridp, ridm, isexe FROM fv"
    );
    while( db_step(&q)==SQLITE_ROW ){
       fossil_print("%3d: ridv=%-4d ridp=%-4d ridm=%-4d chnged=%d isexe=%d\n",
          db_column_int(&q, 0),
          db_column_int(&q, 5),
          db_column_int(&q, 6),
          db_column_int(&q, 7),
          db_column_int(&q, 4),
          db_column_int(&q, 8));
       fossil_print("     fn  = [%s]\n", db_column_text(&q, 1));
       fossil_print("     fnp = [%s]\n", db_column_text(&q, 2));
       fossil_print("     fnm = [%s]\n", db_column_text(&q, 3));
    }
    db_finalize(&q);
  }

  /*
  ** Find files in M and V but not in P and report conflicts.
  ** The file in M will be ignored.  It will be treated as if it
  ** does not exist.
  */
  db_prepare(&q,
    "SELECT idm FROM fv WHERE idp=0 AND idv>0 AND idm>0"
  );
  while( db_step(&q)==SQLITE_ROW ){
    int idm = db_column_int(&q, 0);
    char *zName = db_text(0, "SELECT pathname FROM vfile WHERE id=%d", idm);
    fossil_warning("WARNING - no common ancestor: %s\n", zName);
    free(zName);
    db_multi_exec("UPDATE fv SET idm=0 WHERE idm=%d", idm);
  }
  db_finalize(&q);

  /*
  ** Add to V files that are not in V or P but are in M
  */
  db_prepare(&q,
    "SELECT idm, rowid, fnm FROM fv AS x"
    " WHERE idp=0 AND idv=0 AND idm>0"
  );
  while( db_step(&q)==SQLITE_ROW ){
    int idm = db_column_int(&q, 0);
    int rowid = db_column_int(&q, 1);
    int idv;
    const char *zName;
    db_multi_exec(
      "INSERT INTO vfile(vid,chnged,deleted,rid,mrid,isexe,pathname)"
      "  SELECT %d,3,0,rid,mrid,isexe,pathname FROM vfile WHERE id=%d",
      vid, idm
    );
    idv = db_last_insert_rowid();
    db_multi_exec("UPDATE fv SET idv=%d WHERE rowid=%d", idv, rowid);
    zName = db_column_text(&q, 2);
    fossil_print("ADDED %s\n", zName);
    if( !nochangeFlag ){
      undo_save(zName);
      vfile_to_disk(0, idm, 0, 0);
    }
  }
  db_finalize(&q);

  /*
  ** Find files that have changed from P->M but not P->V.
  ** Copy the M content over into V.
  */
  db_prepare(&q,
    "SELECT idv, ridm, fn FROM fv"
    " WHERE idp>0 AND idv>0 AND idm>0"
    "   AND ridm!=ridp AND ridv=ridp AND NOT chnged"
  );
  while( db_step(&q)==SQLITE_ROW ){
    int idv = db_column_int(&q, 0);
    int ridm = db_column_int(&q, 1);
    const char *zName = db_column_text(&q, 2);
    /* Copy content from idm over into idv.  Overwrite idv. */
    fossil_print("UPDATE %s\n", zName);
    if( !nochangeFlag ){
      undo_save(zName);
      db_multi_exec(
        "UPDATE vfile SET mtime=0, mrid=%d, chnged=2 WHERE id=%d", ridm, idv
      );
      vfile_to_disk(0, idv, 0, 0);
    }
  }
  db_finalize(&q);

  /*
  ** Do a three-way merge on files that have changes on both P->M and P->V.
  */
  db_prepare(&q,
    "SELECT ridm, idv, ridp, ridv, %s, fn, isexe FROM fv"
    " WHERE idp>0 AND idv>0 AND idm>0"
    "   AND ridm!=ridp AND (ridv!=ridp OR chnged)",
    glob_expr("fv.fn", zBinGlob)
  );
  while( db_step(&q)==SQLITE_ROW ){
    int ridm = db_column_int(&q, 0);
    int idv = db_column_int(&q, 1);
    int ridp = db_column_int(&q, 2);
    int ridv = db_column_int(&q, 3);
    int isBinary = db_column_int(&q, 4);
    const char *zName = db_column_text(&q, 5);
    int isExe = db_column_int(&q, 6);
    int rc;
    char *zFullPath;
    Blob m, p, r;
    /* Do a 3-way merge of idp->idm into idp->idv.  The results go into idv. */
    if( detailFlag ){
      fossil_print("MERGE %s  (pivot=%d v1=%d v2=%d)\n", 
                   zName, ridp, ridm, ridv);
    }else{
      fossil_print("MERGE %s\n", zName);
    }
    undo_save(zName);
    zFullPath = mprintf("%s/%s", g.zLocalRoot, zName);
    content_get(ridp, &p);
    content_get(ridm, &m);
    if( isBinary ){
      rc = -1;
      blob_zero(&r);
    }else{
      rc = merge_3way(&p, zFullPath, &m, &r);
    }
    if( rc>=0 ){
      if( !nochangeFlag ){
        blob_write_to_file(&r, zFullPath);
        file_setexe(zFullPath, isExe);
      }
      db_multi_exec("UPDATE vfile SET mtime=0 WHERE id=%d", idv);
      if( rc>0 ){
        fossil_print("***** %d merge conflicts in %s\n", rc, zName);
        nConflict++;
      }
    }else{
      fossil_print("***** Cannot merge binary file %s\n", zName);
      nConflict++;
    }
    blob_reset(&p);
    blob_reset(&m);
    blob_reset(&r);
    db_multi_exec("INSERT OR IGNORE INTO vmerge(id,merge) VALUES(%d,%d)",
                  idv,ridm);
  }
  db_finalize(&q);

  /*
  ** Drop files that are in P and V but not in M
  */
  db_prepare(&q,
    "SELECT idv, fn, chnged FROM fv"
    " WHERE idp>0 AND idv>0 AND idm=0"
  );
  while( db_step(&q)==SQLITE_ROW ){
    int idv = db_column_int(&q, 0);
    const char *zName = db_column_text(&q, 1);
    int chnged = db_column_int(&q, 2);
    /* Delete the file idv */
    fossil_print("DELETE %s\n", zName);
    if( chnged ){
      fossil_warning("WARNING: local edits lost for %s\n", zName);
      nConflict++;
    }
    undo_save(zName);
    db_multi_exec(
      "UPDATE vfile SET deleted=1 WHERE id=%d", idv
    );
    if( !nochangeFlag ){
      char *zFullPath = mprintf("%s%s", g.zLocalRoot, zName);
      file_delete(zFullPath);
      free(zFullPath);
    }
  }
  db_finalize(&q);

  /*
  ** Rename files that have taken a rename on P->M but which keep the same
  ** name o P->V.   If a file is renamed on P->V only or on both P->V and
  ** P->M then we retain the V name of the file.
  */
  db_prepare(&q,
    "SELECT idv, fnp, fnm FROM fv"
    " WHERE idv>0 AND idp>0 AND idm>0 AND fnp=fn AND fnm!=fnp"
  );
  while( db_step(&q)==SQLITE_ROW ){
    int idv = db_column_int(&q, 0);
    const char *zOldName = db_column_text(&q, 1);
    const char *zNewName = db_column_text(&q, 2);
    fossil_print("RENAME %s -> %s\n", zOldName, zNewName);
    undo_save(zOldName);
    undo_save(zNewName);
    db_multi_exec(
      "UPDATE vfile SET pathname=%Q, origname=coalesce(origname,pathname)"
      " WHERE id=%d AND vid=%d", zNewName, idv, vid
    );
    if( !nochangeFlag ){
      char *zFullOldPath = mprintf("%s%s", g.zLocalRoot, zOldName);
      char *zFullNewPath = mprintf("%s%s", g.zLocalRoot, zNewName);
      file_copy(zFullOldPath, zFullNewPath);
      file_delete(zFullOldPath);
      free(zFullNewPath);
      free(zFullOldPath);
    }
  }
  db_finalize(&q);


  /* Report on conflicts
  */
  if( nConflict && !nochangeFlag ){
    fossil_warning(
       "WARNING: merge conflicts - see messages above for details.\n");
  }

  /*
  ** Clean up the mid and pid VFILE entries.  Then commit the changes.
  */
  db_multi_exec("DELETE FROM vfile WHERE vid!=%d", vid);
  if( !pickFlag ){
    db_multi_exec("INSERT OR IGNORE INTO vmerge(id,merge) VALUES(0,%d)", mid);
  }
  undo_finish();
  db_end_transaction(nochangeFlag);
}