#include <unistd.h>
#else
#include <io.h>
#endif

#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include "sqlite3.h"


static struct GlobalData {
  int pagesize;                   /* Size of a database page */
  int dbfd;                       /* File descriptor for reading the DB */
  int mxPage;                     /* Last page number */
  int perLine;                    /* HEX elements to print per line */
  int bRaw;                       /* True to access db file via OS APIs */
  sqlite3_file *pFd;              /* File descriptor for URI mode */
  sqlite3 *pDb;                   /* Database handle that owns pFd */
} g = {1024, -1, 0, 16,   0, 0, 0};


typedef long long int i64;      /* Datatype for 64-bit integers */


/*
** Convert the var-int format into i64.  Return the number of bytes
** in the var-int.  Write the var-int value into *pVal.

/* Report an out-of-memory error and die.
*/
static void out_of_memory(void){
  fprintf(stderr,"Out of memory...\n");
  exit(1);
}

/*
** Open a database connection.
*/
static sqlite3 *openDatabase(const char *zPrg, const char *zName){
  sqlite3 *db = 0;
  int flags = SQLITE_OPEN_READWRITE | SQLITE_OPEN_URI;
  int rc = sqlite3_open_v2(zName, &db, flags, 0);
  if( rc!=SQLITE_OK ){
    const char *zErr = sqlite3_errmsg(db);
    fprintf(stderr, "%s: can't open %s (%s)\n", zPrg, zName, zErr);
    sqlite3_close(db);
    exit(1);
  }
  return db;
}

/**************************************************************************
** Beginning of low-level file access functions.
**
** All low-level access to the database file read by this program is
** performed using the following four functions:
**
**   fileOpen()     - open the db file
**   fileClose()    - close the db file
**   fileRead()     - read raw data from the db file
**   fileGetsize()  - return the size of the db file in bytes
*/

/*
** Open the database file.
*/
static void fileOpen(const char *zPrg, const char *zName){
  assert( g.dbfd<0 );
  if( g.bRaw==0 ){
    int rc;
    void *pArg = (void *)(&g.pFd);
    g.pDb = openDatabase(zPrg, zName);
    rc = sqlite3_file_control(g.pDb, "main", SQLITE_FCNTL_FILE_POINTER, pArg);
    if( rc!=SQLITE_OK ){
      fprintf(stderr, 
          "%s: failed to obtain fd for %s (SQLite too old?)\n", zPrg, zName
      );
      exit(1);
    }
  }else{
    g.dbfd = open(zName, O_RDONLY);
    if( g.dbfd<0 ){
      fprintf(stderr,"%s: can't open %s\n", zPrg, zName);
      exit(1);
    }
  }
}

/*
** Close the database file opened by fileOpen()
*/
static void fileClose(){
  if( g.bRaw==0 ){
    sqlite3_close(g.pDb);
    g.pDb = 0;
    g.pFd = 0;
  }else{
    close(g.dbfd);
    g.dbfd = -1;
  }
}

/*
** Read content from the file.
**
** Space to hold the content is obtained from sqlite3_malloc() and needs 
** to be freed by the caller.
*/
static unsigned char *fileRead(sqlite3_int64 ofst, int nByte){
  unsigned char *aData;
  int got;
  aData = sqlite3_malloc(nByte+32);
  if( aData==0 ) out_of_memory();
  memset(aData, 0, nByte+32);
  if( g.bRaw==0 ){
    int rc = g.pFd->pMethods->xRead(g.pFd, (void*)aData, nByte, ofst);
    if( rc!=SQLITE_OK && rc!=SQLITE_IOERR_SHORT_READ ){
      fprintf(stderr, "error in xRead() - %d\n", rc);
      exit(1);
    }
  }else{
    lseek(g.dbfd, ofst, SEEK_SET);
    got = read(g.dbfd, aData, nByte);
    if( got>0 && got<nByte ) memset(aData+got, 0, nByte-got);
  }
  return aData;
}

/*
** Return the size of the file in byte.
*/
static sqlite3_int64 fileGetsize(void){
  sqlite3_int64 res = 0;
  if( g.bRaw==0 ){
    int rc = g.pFd->pMethods->xFileSize(g.pFd, &res);
    if( rc!=SQLITE_OK ){
      fprintf(stderr, "error in xFileSize() - %d\n", rc);
      exit(1);
    }
  }else{
    struct stat sbuf;
    fstat(g.dbfd, &sbuf);
    res = (sqlite3_int64)(sbuf.st_size);
  }
  return res;
}

/*
** End of low-level file access functions.
**************************************************************************/

/*
** Print a range of bytes as hex and as ascii.
*/
static unsigned char *print_byte_range(
  int ofst,          /* First byte in the range of bytes to print */
  int nByte,         /* Number of bytes to print */
  int printOfst      /* Add this amount to the index on the left column */

    zOfstFmt = " %05x: ";
  }else if( ((printOfst+nByte)&~0xffffff)==0 ){
    zOfstFmt = " %06x: ";
  }else{
    zOfstFmt = " %08x: ";
  }

  aData = fileRead(ofst, nByte);
  for(i=0; i<nByte; i += g.perLine){
    fprintf(stdout, zOfstFmt, i+printOfst);
    for(j=0; j<g.perLine; j++){
      if( i+j>nByte ){
        fprintf(stdout, "   ");
      }else{
        fprintf(stdout,"%02x ", aData[i+j]);
      }
    }
    for(j=0; j<g.perLine; j++){
      if( i+j>nByte ){
        fprintf(stdout, " ");
      }else{
        fprintf(stdout,"%c", isprint(aData[i+j]) ? aData[i+j] : '.');
      }
    }
    fprintf(stdout,"\n");
  }
  return aData;
}

/*
** Print an entire page of content as hex
*/
static void print_page(int iPg){
  int iStart;
  unsigned char *aData;
  iStart = (iPg-1)*g.pagesize;
  fprintf(stdout, "Page %d:   (offsets 0x%x..0x%x)\n",
          iPg, iStart, iStart+g.pagesize-1);
  aData = print_byte_range(iStart, g.pagesize, 0);
  sqlite3_free(aData);
}


/* Print a line of decode output showing a 4-byte integer.
*/
static void print_decode_line(
  unsigned char *aData,      /* Content being decoded */

static i64 localPayload(i64 nPayload, char cType){
  i64 maxLocal;
  i64 minLocal;
  i64 surplus;
  i64 nLocal;
  if( cType==13 ){
    /* Table leaf */
    maxLocal = g.pagesize-35;
    minLocal = (g.pagesize-12)*32/255-23;
  }else{
    maxLocal = (g.pagesize-12)*64/255-23;
    minLocal = (g.pagesize-12)*32/255-23;
  }
  if( nPayload>maxLocal ){
    surplus = minLocal + (nPayload-minLocal)%(g.pagesize-4);
    if( surplus<=maxLocal ){
      nLocal = surplus;
    }else{
      nLocal = minLocal;
    }
  }else{
    nLocal = nPayload;

  if( a[0]==2 || a[0]==5 ){
    print_decode_line(a, 8, 4, "Right child");
  }
  if( cellToDecode==(-2) && nCell>0 ){
    printf(" key: lx=left-child n=payload-size r=rowid\n");
  }
  if( showMap ){
    zMap = sqlite3_malloc(g.pagesize);
    memset(zMap, '.', g.pagesize);
    memset(zMap, '1', hdrSize);
    memset(&zMap[hdrSize], 'H', iCellPtr);
    memset(&zMap[hdrSize+iCellPtr], 'P', 2*nCell);
  }
  for(i=0; i<nCell; i++){
    int cofst = iCellPtr + i*2;
    char *zDesc;

      printf(" %03x: cell[%d] %s\n", cofst, i, zDesc);
    }else if( cellToDecode==(-1) || cellToDecode==i ){
      decodeCell(a, pgno, i, hdrSize, cofst-hdrSize);
    }
  }
  if( showMap ){
    printf("Page map:  (H=header P=cell-index 1=page-1-header .=free-space)\n");
    for(i=0; i<g.pagesize; i+=64){
      printf(" %03x: %.64s\n", i, &zMap[i]);
    }
    sqlite3_free(zMap);
  }
}

/*
** Decode a freelist trunk page.
*/
static void decode_trunk_page(
  int pgno,             /* The page number */

  int detail,           /* Show leaf pages if true */
  int recursive         /* Follow the trunk change if true */
){
  int n, i;
  unsigned char *a;
  while( pgno>0 ){
    a = fileRead((pgno-1)*g.pagesize, g.pagesize);
    printf("Decode of freelist trunk page %d:\n", pgno);
    print_decode_line(a, 0, 4, "Next freelist trunk page");
    print_decode_line(a, 4, 4, "Number of entries on this page");
    if( detail ){
      n = (int)decodeInt32(&a[4]);
      for(i=0; i<n; i++){
        unsigned int x = decodeInt32(&a[8+4*i]);
        char zIdx[10];
        sprintf(zIdx, "[%d]", i);
        printf("  %5s %7u", zIdx, x);
        if( i%5==4 ) printf("\n");
      }
      if( i%5!=0 ) printf("\n");
    }
    if( !recursive ){
      pgno = 0;
    }else{
      pgno = (int)decodeInt32(&a[0]);
    }
    sqlite3_free(a);
  }
}

/*
** A short text comment on the use of each page.
*/
static char **zPageUse;

/*
** Add a comment on the use of a page.
*/
static void page_usage_msg(int pgno, const char *zFormat, ...){
  va_list ap;
  char *zMsg;

  va_start(ap, zFormat);
  zMsg = sqlite3_vmprintf(zFormat, ap);
  va_end(ap);
  if( pgno<=0 || pgno>g.mxPage ){
    printf("ERROR: page %d out of range 1..%d: %s\n",
            pgno, g.mxPage, zMsg);
    sqlite3_free(zMsg);
    return;
  }
  if( zPageUse[pgno]!=0 ){
    printf("ERROR: page %d used multiple times:\n", pgno);
    printf("ERROR:    previous: %s\n", zPageUse[pgno]);
    printf("ERROR:    current:  %s\n", zMsg);

    i = decodeVarint(a, &rowid);
    a += i;
    n += i;
  }
  if( nLocal<nPayload ){
    int ovfl = decodeInt32(a+nLocal);
    int cnt = 0;
    while( ovfl && (cnt++)<g.mxPage ){
      page_usage_msg(ovfl, "overflow %d from cell %d of page %d",
                     cnt, cellno, pgno);
      a = fileRead((ovfl-1)*g.pagesize, 4);
      ovfl = decodeInt32(a);
      sqlite3_free(a);
    }
  }
}


/*
** Describe the usages of a b-tree page
*/
static void page_usage_btree(
  int pgno,             /* Page to describe */
  int parent,           /* Parent of this page.  0 for root pages */
  int idx,              /* Which child of the parent */
  const char *zName     /* Name of the table */
){
  unsigned char *a;
  const char *zType = "corrupt node";
  int nCell;
  int i;
  int hdr = pgno==1 ? 100 : 0;

  if( pgno<=0 || pgno>g.mxPage ) return;
  a = fileRead((pgno-1)*g.pagesize, g.pagesize);
  switch( a[hdr] ){
    case 2:  zType = "interior node of index";  break;
    case 5:  zType = "interior node of table";  break;
    case 10: zType = "leaf of index";           break;
    case 13: zType = "leaf of table";           break;
  }
  if( parent ){

    for(i=0; i<nCell; i++){
      int ofst;
      ofst = cellstart + i*2;
      ofst = a[ofst]*256 + a[ofst+1];
      page_usage_cell(a[hdr], a+ofst, pgno, i);
    }
  }
  sqlite3_free(a);
}

/*
** Determine page usage by the freelist
*/
static void page_usage_freelist(int pgno){
  unsigned char *a;
  int cnt = 0;
  int i;
  int n;
  int iNext;
  int parent = 1;

  while( pgno>0 && pgno<=g.mxPage && (cnt++)<g.mxPage ){
    page_usage_msg(pgno, "freelist trunk #%d child of %d", cnt, parent);
    a = fileRead((pgno-1)*g.pagesize, g.pagesize);
    iNext = decodeInt32(a);
    n = decodeInt32(a+4);
    for(i=0; i<n; i++){
      int child = decodeInt32(a + (i*4+8));
      page_usage_msg(child, "freelist leaf, child %d of trunk page %d",
                     i, pgno);
    }
    sqlite3_free(a);
    parent = pgno;
    pgno = iNext;
  }
}

/*
** Determine pages used as PTRMAP pages
*/
static void page_usage_ptrmap(unsigned char *a){
  if( a[55] ){
    int usable = g.pagesize - a[20];
    int pgno = 2;
    int perPage = usable/5;
    while( pgno<=g.mxPage ){
      page_usage_msg(pgno, "PTRMAP page covering %d..%d",
                           pgno+1, pgno+perPage);
      pgno += perPage + 1;
    }
  }
}

/*
** Try to figure out how every page in the database file is being used.
*/
static void page_usage_report(const char *zPrg, const char *zDbName){
  int i, j;
  int rc;
  sqlite3 *db;
  sqlite3_stmt *pStmt;
  unsigned char *a;
  char zQuery[200];

  /* Avoid the pathological case */
  if( g.mxPage<1 ){
    printf("empty database\n");
    return;
  }

  /* Open the database file */


  db = openDatabase(zPrg, zDbName);




  /* Set up global variables zPageUse[] and g.mxPage to record page
  ** usages */
  zPageUse = sqlite3_malloc( sizeof(zPageUse[0])*(g.mxPage+1) );
  if( zPageUse==0 ) out_of_memory();
  memset(zPageUse, 0, sizeof(zPageUse[0])*(g.mxPage+1));

  /* Discover the usage of each page */
  a = fileRead(0, 100);
  page_usage_freelist(decodeInt32(a+32));
  page_usage_ptrmap(a);
  sqlite3_free(a);
  page_usage_btree(1, 0, 0, "sqlite_master");
  sqlite3_exec(db, "PRAGMA writable_schema=ON", 0, 0, 0);
  for(j=0; j<2; j++){
    sqlite3_snprintf(sizeof(zQuery), zQuery,
             "SELECT type, name, rootpage FROM SQLITE_MASTER WHERE rootpage"
             " ORDER BY rowid %s", j?"DESC":"");
    rc = sqlite3_prepare_v2(db, zQuery, -1, &pStmt, 0);

    }
    rc = sqlite3_finalize(pStmt);
    if( rc==SQLITE_OK ) break;
  }
  sqlite3_close(db);

  /* Print the report and free memory used */
  for(i=1; i<=g.mxPage; i++){
    printf("%5d: %s\n", i, zPageUse[i] ? zPageUse[i] : "???");
    sqlite3_free(zPageUse[i]);
  }
  sqlite3_free(zPageUse);
  zPageUse = 0;
}

/*
** Try to figure out how every page in the database file is being used.
*/
static void ptrmap_coverage_report(const char *zDbName){
  int pgno;
  unsigned char *aHdr;
  unsigned char *a;
  int usable;
  int perPage;
  int i;

  /* Avoid the pathological case */
  if( g.mxPage<1 ){
    printf("empty database\n");
    return;
  }

  /* Make sure PTRMAPs are used in this database */
  aHdr = fileRead(0, 100);
  if( aHdr[55]==0 ){
    printf("database does not use PTRMAP pages\n");
    return;
  }
  usable = g.pagesize - aHdr[20];
  perPage = usable/5;
  sqlite3_free(aHdr);
  printf("%5d: root of sqlite_master\n", 1);
  for(pgno=2; pgno<=g.mxPage; pgno += perPage+1){
    printf("%5d: PTRMAP page covering %d..%d\n", pgno,
           pgno+1, pgno+perPage);
    a = fileRead((pgno-1)*g.pagesize, usable);
    for(i=0; i+5<=usable && pgno+1+i/5<=g.mxPage; i+=5){
      const char *zType = "???";
      unsigned int iFrom = decodeInt32(&a[i+1]);
      switch( a[i] ){
        case 1:  zType = "b-tree root page";        break;
        case 2:  zType = "freelist page";           break;
        case 3:  zType = "first page of overflow";  break;
        case 4:  zType = "later page of overflow";  break;
        case 5:  zType = "b-tree non-root page";    break;
      }
      printf("%5d: %s, parent=%u\n", pgno+1+i/5, zType, iFrom);
    }
    sqlite3_free(a);
  }
}

/*
** Print a usage comment
*/
static void usage(const char *argv0){
  fprintf(stderr, "Usage %s ?--uri? FILENAME ?args...?\n\n", argv0);
  fprintf(stderr,
    "switches:\n"
    "    --raw           Read db file directly, bypassing SQLite VFS\n"
    "args:\n"
    "    dbheader        Show database header\n"
    "    pgidx           Index of how each page is used\n"
    "    ptrmap          Show all PTRMAP page content\n"
    "    NNN..MMM        Show hex of pages NNN through MMM\n"
    "    NNN..end        Show hex of pages NNN through end of file\n"
    "    NNNb            Decode btree page NNN\n"
    "    NNNbc           Decode btree page NNN and show content\n"
    "    NNNbm           Decode btree page NNN and show a layout map\n"
    "    NNNbdCCC        Decode cell CCC on btree page NNN\n"
    "    NNNt            Decode freelist trunk page NNN\n"
    "    NNNtd           Show leaf freelist pages on the decode\n"
    "    NNNtr           Recursively decode freelist starting at NNN\n"
  );
}

int main(int argc, char **argv){
  sqlite3_int64 szFile;
  unsigned char *zPgSz;
  const char *zPrg = argv[0];     /* Name of this executable */
  char **azArg = argv;
  int nArg = argc;

  /* Check for the "--uri" or "-uri" switch. */
  if( nArg>1 ){
    if( sqlite3_stricmp("-raw", azArg[1])==0 
     || sqlite3_stricmp("--raw", azArg[1])==0
    ){
      g.bRaw = 1;
      azArg++;
      nArg--;
    }
  }

  if( nArg<2 ){

    usage(zPrg);
    exit(1);
  }

  fileOpen(zPrg, azArg[1]);
  szFile = fileGetsize();

  zPgSz = fileRead(16, 2);
  g.pagesize = zPgSz[0]*256 + zPgSz[1]*65536;
  if( g.pagesize==0 ) g.pagesize = 1024;
  sqlite3_free(zPgSz);

  printf("Pagesize: %d\n", g.pagesize);
  g.mxPage = (szFile+g.pagesize-1)/g.pagesize;


  printf("Available pages: 1..%d\n", g.mxPage);
  if( nArg==2 ){
    int i;
    for(i=1; i<=g.mxPage; i++) print_page(i);
  }else{
    int i;
    for(i=2; i<nArg; i++){
      int iStart, iEnd;
      char *zLeft;
      if( strcmp(azArg[i], "dbheader")==0 ){
        print_db_header();
        continue;
      }
      if( strcmp(azArg[i], "pgidx")==0 ){
        page_usage_report(zPrg, azArg[1]);
        continue;
      }
      if( strcmp(azArg[i], "ptrmap")==0 ){
        ptrmap_coverage_report(azArg[1]);
        continue;
      }
      if( strcmp(azArg[i], "help")==0 ){
        usage(zPrg);
        continue;
      }
      if( !isdigit(azArg[i][0]) ){
        fprintf(stderr, "%s: unknown option: [%s]\n", zPrg, azArg[i]);
        continue;
      }
      iStart = strtol(azArg[i], &zLeft, 0);
      if( zLeft && strcmp(zLeft,"..end")==0 ){
        iEnd = g.mxPage;
      }else if( zLeft && zLeft[0]=='.' && zLeft[1]=='.' ){
        iEnd = strtol(&zLeft[2], 0, 0);
      }else if( zLeft && zLeft[0]=='b' ){
        int ofst, nByte, hdrSize;
        unsigned char *a;
        if( iStart==1 ){
          ofst = hdrSize = 100;
          nByte = g.pagesize-100;
        }else{
          hdrSize = 0;
          ofst = (iStart-1)*g.pagesize;
          nByte = g.pagesize;
        }
        a = fileRead(ofst, nByte);
        decode_btree_page(a, iStart, hdrSize, &zLeft[1]);
        sqlite3_free(a);
        continue;
      }else if( zLeft && zLeft[0]=='t' ){
        int detail = 0;
        int recursive = 0;
        int i;
        for(i=1; zLeft[i]; i++){
          if( zLeft[i]=='r' ) recursive = 1;
          if( zLeft[i]=='d' ) detail = 1;
        }
        decode_trunk_page(iStart, detail, recursive);
        continue;
      }else{
        iEnd = iStart;
      }
      if( iStart<1 || iEnd<iStart || iEnd>g.mxPage ){
        fprintf(stderr,
          "Page argument should be LOWER?..UPPER?.  Range 1 to %d\n",
          g.mxPage);
        exit(1);
      }
      while( iStart<=iEnd ){
        print_page(iStart);
        iStart++;
      }
    }
  }
  fileClose();
  return 0;
}