/*
 * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
 *
 * This code is derived from software contributed to The DragonFly Project
 * by Matthew Dillon <dillon@backplane.com>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name of The DragonFly Project nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific, prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $DragonFly: src/usr.bin/undo/undo.c,v 1.6 2008/07/17 21:34:47 thomas Exp $
 */
/*
 * UNDO - retrieve an older version of a file.
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <sys/tree.h>
#include <sys/ioctl.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <err.h>
#include <vfs/hammer/hammer_disk.h>
#include <vfs/hammer/hammer_ioctl.h>

/*
 * Sorted list of transaction ids
 */
struct undo_hist_entry;
RB_HEAD(undo_hist_entry_rb_tree, undo_hist_entry);
RB_PROTOTYPE2(undo_hist_entry_rb_tree, undo_hist_entry, rbnode,
        undo_hist_entry_compare, hammer_tid_t);

struct undo_hist_entry {
        RB_ENTRY(undo_hist_entry) rbnode;
        struct hammer_ioc_hist_entry tse;
        ino_t inum;
};

enum undo_type { TYPE_FILE, TYPE_DIFF, TYPE_RDIFF, TYPE_HISTORY };
enum undo_cmd { CMD_DUMP, CMD_ITERATEALL };

#define UNDO_FLAG_MULT          0x0001
#define UNDO_FLAG_INOCHG        0x0002
#define UNDO_FLAG_TID_INDEX1    0x0004
#define UNDO_FLAG_TID_INDEX2    0x0008

static int undo_hist_entry_compare(struct undo_hist_entry *he1,
                    struct undo_hist_entry *he2);
static void doiterate(const char *filename, int flags,
                   struct hammer_ioc_hist_entry ts1,
                   struct hammer_ioc_hist_entry ts2,
                   enum undo_cmd cmd, enum undo_type type);
static int doiterate_dump(const char *filename, int flags,
                   struct undo_hist_entry_rb_tree *ptse_tree,
                   struct hammer_ioc_hist_entry ts1,
                   struct hammer_ioc_hist_entry ts2,
                   enum undo_type type);
static int doiterate_iterall(const char *filename, int flags,
                   struct undo_hist_entry_rb_tree *ptse_tree,
                   enum undo_type type);
static void dogenerate(const char *filename, int flags,
                   struct hammer_ioc_hist_entry ts1,
                   struct hammer_ioc_hist_entry ts2,
                   int idx, enum undo_type type);
static void __collect_history(int fd, int *error,
                   struct undo_hist_entry_rb_tree *tse_tree);
static void collect_history(const char *filename, int *errorp,
                   struct undo_hist_entry_rb_tree *dir_tree);
static void collect_dir_history(const char *filename, int *error,
                   struct undo_hist_entry_rb_tree *dir_tree);
static void clean_tree(struct undo_hist_entry_rb_tree *tree);
static hammer_tid_t parse_delta_time(const char *timeStr, int *flags,
                   int ind_flag);
static FILE *_fopen(const char *filename, const char *mode);
static void runcmd(int fd, const char *cmd, ...);
static char *timestamp(struct hammer_ioc_hist_entry *hen);
static void usage(void);

static int VerboseOpt;
static const char *OutFileName = NULL;
static const char *OutFilePostfix = NULL;

RB_GENERATE2(undo_hist_entry_rb_tree, undo_hist_entry, rbnode,
        undo_hist_entry_compare, hammer_tid_t, tse.tid);


int
main(int ac, char **av)
{
        enum undo_cmd cmd;
        enum undo_type type;
        struct hammer_ioc_hist_entry ts1;
        struct hammer_ioc_hist_entry ts2;
        int c;
        int count_t;
        int flags;

        bzero(&ts1, sizeof(ts1));
        bzero(&ts2, sizeof(ts2));

        cmd = CMD_DUMP;
        type = TYPE_FILE;
        count_t = 0;
        flags = 0;

        while ((c = getopt(ac, av, "adDiuvo:t:")) != -1) {
                switch(c) {
                case 'd':
                        type = TYPE_DIFF;
                        break;
                case 'D':
                        type = TYPE_RDIFF;
                        break;
                case 'i':
                        if (type != TYPE_FILE)
                                usage();
                        type = TYPE_HISTORY;
                        cmd = CMD_ITERATEALL;
                        break;
                case 'a':
                        cmd = CMD_ITERATEALL;
                        break;
                case 'u':
                        OutFilePostfix = ".undo";
                        break;
                case 'v':
                        ++VerboseOpt;
                        break;
                case 'o':
                        OutFileName = optarg;
                        break;
                case 't':
                        /*
                         * Parse one or two -t options.  If two are specified
                         * -d is implied (but may be overridden)
                         */
                        ++count_t;
                        if (count_t == 1) {
                                ts1.tid = parse_delta_time(optarg, &flags,
                                                        UNDO_FLAG_TID_INDEX1);
                        } else if (count_t == 2) {
                                ts2.tid = parse_delta_time(optarg, &flags,
                                                        UNDO_FLAG_TID_INDEX2);
                                if (type == TYPE_FILE)
                                        type = TYPE_DIFF;
                        } else {
                                usage();
                        }
                        break;
                default:
                        usage();
                        /* NOT REACHED */
                        break;
                }
        }

        /*
         * Option validation
         */
        if (OutFileName && OutFilePostfix) {
                fprintf(stderr, "The -o option may not be combined with -u\n");
                usage();
        }

        ac -= optind;
        av += optind;
        if (ac > 1)
                flags |= UNDO_FLAG_MULT;

        if (ac == 0)
                usage();

        /*
         * Validate the output template, if specified.
         */
        if (OutFileName && (flags & UNDO_FLAG_MULT)) {
                const char *ptr = OutFileName;
                int didStr = 0;

                while ((ptr = strchr(ptr, '%')) != NULL) {
                        if (ptr[1] == 's') {
                                if (didStr) {
                                        fprintf(stderr, "Malformed output "
                                                        "template\n");
                                        usage();
                                }
                                didStr = 1;
                                ++ptr;
                        } else if (ptr[1] != '%') {
                                fprintf(stderr, "Malformed output template\n");
                                usage();
                        } else {
                                ptr += 2;
                        }
                }
        }

        while (ac) {
                doiterate(*av, flags, ts1, ts2, cmd, type);
                ++av;
                --ac;
        }
        return(0);
}

/*
 * Iterate through a file's history.  If cmd == CMD_DUMP we take the
 * next-to-last transaction id, unless another given.  Otherwise if
 * cmd == CMD_ITERATEALL we scan all transaction ids.
 *
 * Also iterate through the directory's history to locate other inodes that
 * used the particular file name.
 */
static
void
doiterate(const char *filename, int flags,
          struct hammer_ioc_hist_entry ts1,
          struct hammer_ioc_hist_entry ts2,
          enum undo_cmd cmd, enum undo_type type)
{
        struct undo_hist_entry_rb_tree dir_tree;
        struct undo_hist_entry_rb_tree tse_tree;
        struct undo_hist_entry *tse;
        struct stat sb;
        char *path = NULL;
        int error;

        RB_INIT(&dir_tree);
        RB_INIT(&tse_tree);

        /*
         * Use the directory history to locate all possible versions of
         * the file.
         */
        collect_dir_history(filename, &error, &dir_tree);
        RB_FOREACH(tse, undo_hist_entry_rb_tree, &dir_tree) {
                asprintf(&path, "%s@@0x%016jx", filename, (uintmax_t)tse->tse.tid);
                if (stat(path, &sb) == 0 && (sb.st_mode & S_IFIFO)) {
                        fprintf(stderr, "Warning: fake transaction id %s@@0x%016jx\n",
                                filename,
                                (uintmax_t)tse->tse.tid);
                        free(path);
                        continue;
                }
                collect_history(path, &error, &tse_tree);
                free(path);
        }
        collect_history(filename, &error, &tse_tree);

        switch (cmd) {
        case CMD_DUMP:
                if (doiterate_dump(filename, flags, &tse_tree, ts1, ts2, type) == -1)
                        printf("%s: No UNDO history found\n", filename);
                break;
        case CMD_ITERATEALL:
                if (doiterate_iterall(filename, flags, &tse_tree, type) == -1)
                        printf("%s: No UNDO history found\n", filename);
                break;
        default:
                fprintf(stderr, "Invalid command %d\n", cmd);
                break;
        }

        clean_tree(&dir_tree);
        clean_tree(&tse_tree);
}

static
int
doiterate_dump(const char *filename, int flags,
                struct undo_hist_entry_rb_tree *ptse_tree,
                struct hammer_ioc_hist_entry ts1,
                struct hammer_ioc_hist_entry ts2,
                enum undo_type type)
{
        struct undo_hist_entry *tse1;
        struct undo_hist_entry *tse2;

        /*
         * Find entry if tid set to placeholder index
         */
        if (flags & UNDO_FLAG_TID_INDEX1) {
                tse1 = RB_MAX(undo_hist_entry_rb_tree, ptse_tree);
                while (tse1 && ts1.tid--) {
                        tse1 = RB_PREV(undo_hist_entry_rb_tree,
                                       ptse_tree, tse1);
                }
                if (tse1)
                        ts1 = tse1->tse;
                else
                        ts1.tid = 0;
        }
        if (flags & UNDO_FLAG_TID_INDEX2) {
                tse2 = RB_MAX(undo_hist_entry_rb_tree, ptse_tree);
                while (tse2 && ts2.tid--) {
                        tse2 = RB_PREV(undo_hist_entry_rb_tree,
                                       ptse_tree, tse2);
                }
                if (tse2)
                        ts2 = tse2->tse;
                else
                        ts2.tid = 0;
        }

        /*
         * Single entry, most recent prior to current
         */
        if (ts1.tid == 0) {
                tse2 = RB_MAX(undo_hist_entry_rb_tree, ptse_tree);
                if (tse2) {
                        ts2 = tse2->tse;
                        tse1 = RB_PREV(undo_hist_entry_rb_tree,
                                       ptse_tree, tse2);
                        if (tse1)
                                ts1 = tse1->tse;
                }
        }

        if (ts1.tid) {
                dogenerate(filename, 0, ts1, ts2, 0, type);
                return(0);
        }
        return(-1);
}

static
int
doiterate_iterall(const char *filename, int flags,
                struct undo_hist_entry_rb_tree *ptse_tree,
                enum undo_type type)
{
        struct undo_hist_entry *tse1;
        struct undo_hist_entry *tse2;
        struct hammer_ioc_hist_entry tid_max;
        int i;

        if (RB_ROOT(ptse_tree) == NULL)
                return(-1);

        /*
         * Iterate entire history
         */
        printf("%s: ITERATE ENTIRE HISTORY\n", filename);

        tse1 = NULL;
        i = 0;
        RB_FOREACH(tse2, undo_hist_entry_rb_tree, ptse_tree) {
                if (tse1) {
                        dogenerate(filename, flags, tse1->tse, tse2->tse, i, type);
                }
                if (tse1 && tse2->inum != tse1->inum)
                        flags |= UNDO_FLAG_INOCHG;
                else
                        flags &= ~UNDO_FLAG_INOCHG;
                tse1 = tse2;
                ++i;
        }

        /*
         * There is no delta to print for the last pair,
         * because they are identical.
         */
        if (type != TYPE_DIFF && type != TYPE_RDIFF) {
                tid_max.tid = HAMMER_MAX_TID;
                tid_max.time32 = 0;
                dogenerate(filename, flags, tse1->tse, tid_max, i, type);
        }
        return(0);
}

/*
 * Generate output for a file as-of ts1 (ts1 may be 0!), if diffing then
 * through ts2.
 */
static
void
dogenerate(const char *filename, int flags,
           struct hammer_ioc_hist_entry ts1,
           struct hammer_ioc_hist_entry ts2,
           int idx, enum undo_type type)
{
        struct stat st;
        const char *elm;
        char *ipath1 = NULL;
        char *ipath2 = NULL;
        FILE *fi;
        FILE *fp;
        char *buf;
        char *path;
        time_t t;
        struct tm *tp;
        char datestr[64];
        int n;

        /*
         * Open the input file.  If ts1 is 0 try to locate the most recent
         * version of the file prior to the current version.
         */
        if (ts1.tid == 0)
                asprintf(&ipath1, "%s", filename);
        else
                asprintf(&ipath1, "%s@@0x%016jx", filename, (uintmax_t)ts1.tid);

        if (ts2.tid == 0)
                asprintf(&ipath2, "%s", filename);
        else
                asprintf(&ipath2, "%s@@0x%016jx", filename, (uintmax_t)ts2.tid);

        if (lstat(ipath1, &st) < 0 && lstat(ipath2, &st) < 0) {
                if (idx == 0 || VerboseOpt) {
                        fprintf(stderr, "Unable to access either %s or %s\n",
                                ipath1, ipath2);
                }
                free(ipath1);
                free(ipath2);
                return;
        }

        /*
         * elm is the last component of the input file name
         */
        if ((elm = strrchr(filename, '/')) != NULL)
                ++elm;
        else
                elm = filename;

        /*
         * Where do we stuff our output?
         */
        if (OutFileName) {
                if (flags & UNDO_FLAG_MULT) {
                        asprintf(&path, OutFileName, elm);
                        fp = _fopen(path, "w");
                        free(path);
                } else {
                        fp = _fopen(OutFileName, "w");
                }
        } else if (OutFilePostfix) {
                if (idx >= 0) {
                        asprintf(&path, "%s%s.%04d", filename,
                                 OutFilePostfix, idx);
                } else {
                        asprintf(&path, "%s%s", filename, OutFilePostfix);
                }
                fp = _fopen(path, "w");
                free(path);
        } else {
                if ((flags & UNDO_FLAG_MULT) && type == TYPE_FILE) {
                        if (idx >= 0) {
                                printf("\n>>> %s %04d 0x%016jx %s\n\n",
                                       filename, idx, (uintmax_t)ts1.tid,
                                       timestamp(&ts1));
                        } else {
                                printf("\n>>> %s ---- 0x%016jx %s\n\n",
                                       filename, (uintmax_t)ts1.tid,
                                       timestamp(&ts1));
                        }
                } else if (idx >= 0 && type == TYPE_FILE) {
                        printf("\n>>> %s %04d 0x%016jx %s\n\n",
                               filename, idx, (uintmax_t)ts1.tid,
                               timestamp(&ts1));
                }
                fp = stdout;
        }

        switch(type) {
        case TYPE_FILE:
                buf = malloc(8192);
                if (buf == NULL)
                        err(1, "malloc");
                if ((fi = fopen(ipath1, "r")) != NULL) {
                        while ((n = fread(buf, 1, 8192, fi)) > 0)
                                fwrite(buf, 1, n, fp);
                        fclose(fi);
                }
                free(buf);
                break;
        case TYPE_DIFF:
                printf("diff -N -r -u %s %s (to %s)\n",
                       ipath1, ipath2, timestamp(&ts2));
                fflush(stdout);
                runcmd(fileno(fp), "/usr/bin/diff", "diff", "-N", "-r", "-u",
                        ipath1, ipath2, NULL);
                break;
        case TYPE_RDIFF:
                printf("diff -N -r -u %s %s\n", ipath2, ipath1);
                fflush(stdout);
                runcmd(fileno(fp), "/usr/bin/diff", "diff", "-N", "-r", "-u",
                        ipath2, ipath1, NULL);
                break;
        case TYPE_HISTORY:
                t = (time_t)ts1.time32;
                tp = localtime(&t);
                strftime(datestr, sizeof(datestr), "%d-%b-%Y %H:%M:%S", tp);
                printf("\t0x%016jx %s", (uintmax_t)ts1.tid, datestr);
                if (flags & UNDO_FLAG_INOCHG)
                        printf(" inode-change");
                if (lstat(ipath1, &st) < 0)
                        printf(" file-deleted");
                printf("\n");
                break;
        }

        if (fp != stdout)
                fclose(fp);
}

static
void
clean_tree(struct undo_hist_entry_rb_tree *tree)
{
        struct undo_hist_entry *tse;

        while ((tse = RB_ROOT(tree)) != NULL) {
                RB_REMOVE(undo_hist_entry_rb_tree, tree, tse);
                free(tse);
        }
}

static
void
__collect_history(int fd, int *errorp, struct undo_hist_entry_rb_tree *tse_tree)
{
        struct hammer_ioc_history hist;
        struct undo_hist_entry *tse;
        struct stat st;
        int i;

        /*
         * Setup
         */
        bzero(&hist, sizeof(hist));
        hist.beg_tid = HAMMER_MIN_TID;
        hist.end_tid = HAMMER_MAX_TID;
        hist.head.flags |= HAMMER_IOC_HISTORY_ATKEY;
        hist.key = 0;
        hist.nxt_key = HAMMER_MAX_KEY;

        *errorp = 0;

        /*
         * Save the inode so inode changes can be reported.
         */
        st.st_ino = 0;
        fstat(fd, &st);

        /*
         * Collect a unique set of transaction ids
         */
        if (ioctl(fd, HAMMERIOC_GETHISTORY, &hist) < 0) {
                *errorp = errno;
                return;
        }
        for (;;) {
                for (i = 0; i < hist.count; ++i) {
                        tse = malloc(sizeof(*tse));
                        tse->tse = hist.hist_ary[i];
                        tse->inum = st.st_ino;
                        if (RB_INSERT(undo_hist_entry_rb_tree, tse_tree, tse)) {
                                free(tse);
                        }
                }
                if (hist.head.flags & HAMMER_IOC_HISTORY_EOF)
                        break;
                if (hist.head.flags & HAMMER_IOC_HISTORY_NEXT_KEY) {
                        hist.key = hist.nxt_key;
                        hist.nxt_key = HAMMER_MAX_KEY;
                }
                if (hist.head.flags & HAMMER_IOC_HISTORY_NEXT_TID)
                        hist.beg_tid = hist.nxt_tid;
                if (ioctl(fd, HAMMERIOC_GETHISTORY, &hist) < 0) {
                        *errorp = errno;
                        break;
                }
        }
}

static
void
collect_history(const char *filename, int *errorp,
                struct undo_hist_entry_rb_tree *dir_tree)
{
        int fd;

        fd = open(filename, O_RDONLY);
        if (fd == -1) {
                *errorp = errno;
                return;
        }
        __collect_history(fd, errorp, dir_tree);
        close(fd);
}

static
void
collect_dir_history(const char *filename, int *errorp,
                    struct undo_hist_entry_rb_tree *dir_tree)
{
        char *dirname;

        if (strrchr(filename, '/')) {
                dirname = strdup(filename);
                *strrchr(dirname, '/') = 0;
        } else {
                dirname = strdup(".");
        }

        collect_history(dirname, errorp, dir_tree);
        free(dirname);
}

static
hammer_tid_t
parse_delta_time(const char *timeStr, int *flags, int ind_flag)
{
        hammer_tid_t tid;

        tid = strtoull(timeStr, NULL, 0);
        if (timeStr[0] == '+')
                ++timeStr;
        if (timeStr[0] >= '0' && timeStr[0] <= '9' && timeStr[1] != 'x')
                *flags |= ind_flag;
        return(tid);
}

static
FILE*
_fopen(const char *filename, const char *mode)
{
        FILE *fp;

        fp = fopen(filename, mode);
        if (fp == NULL)
                err(1, "%s", filename);
        return(fp);
}

static void
runcmd(int fd, const char *cmd, ...)
{
        va_list va;
        pid_t pid;
        char **av;
        int ac;
        int i;

        va_start(va, cmd);
        for (ac = 0; va_arg(va, void *) != NULL; ++ac)
                ;
        va_end(va);

        av = malloc((ac + 1) * sizeof(char *));
        va_start(va, cmd);
        for (i = 0; i < ac; ++i)
                av[i] = va_arg(va, char *);
        va_end(va);
        av[i] = NULL;

        if ((pid = fork()) < 0) {
                err(1, "fork");
        } else if (pid == 0) {
                if (fd != 1) {
                        dup2(fd, 1);
                        close(fd);
                }
                execv(cmd, av);
                _exit(1);
        } else {
                while (waitpid(pid, NULL, 0) != pid)
                        ;
        }
        free(av);
}

/*
 * Convert tid to timestamp.
 */
static char *
timestamp(struct hammer_ioc_hist_entry *hen)
{
        static char timebuf[64];
        time_t t = (time_t)hen->time32;
        struct tm *tp;

        tp = localtime(&t);
        strftime(timebuf, sizeof(timebuf), "%d-%b-%Y %H:%M:%S", tp);
        return(timebuf);
}

static
int
undo_hist_entry_compare(struct undo_hist_entry *he1,
                        struct undo_hist_entry *he2)
{
        if (he1->tse.tid < he2->tse.tid)
                return(-1);
        if (he1->tse.tid > he2->tse.tid)
                return(1);
        return(0);
}

static void
usage(void)
{
        fprintf(stderr, "undo [-adDiuv] [-o outfile] "
                        "[-t transaction-id] [-t transaction-id] path...\n"
                        "    -a       Iterate all historical segments\n"
                        "    -d       Forward diff\n"
                        "    -D       Reverse diff\n"
                        "    -i       Dump history transaction ids\n"
                        "    -u       Generate .undo files\n"
                        "    -v       Verbose\n"
                        "    -o file  Output to the specified file\n"
                        "    -t TID   Retrieve as of transaction-id, TID\n"
                        "             (a second `-t TID' to diff two)\n"
                        "    transaction ids must be prefixed with 0x, and\n"
                        "    otherwise may specify an index starting at 0\n"
                        "    and iterating backwards through the history.\n"
        );
        exit(1);
}