/**
 * Copyright (c) 2017, Timothy Stack
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 * * 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.
 * * Neither the name of Timothy Stack 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 REGENTS 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 REGENTS 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.
 */

#include "config.h"

#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>
#include <glob.h>
#include <grp.h>
#include <pwd.h>

#include "auto_mem.hh"
#include "base/lnav_log.hh"
#include "sql_util.hh"
#include "vtab_module.hh"
#include "fstat_vtab.hh"

using namespace std;

enum {
    FSTAT_COL_PARENT,
    FSTAT_COL_NAME,
    FSTAT_COL_DEV,
    FSTAT_COL_INO,
    FSTAT_COL_TYPE,
    FSTAT_COL_MODE,
    FSTAT_COL_NLINK,
    FSTAT_COL_UID,
    FSTAT_COL_USER,
    FSTAT_COL_GID,
    FSTAT_COL_GROUP,
    FSTAT_COL_RDEV,
    FSTAT_COL_SIZE,
    FSTAT_COL_BLKSIZE,
    FSTAT_COL_BLOCKS,
    FSTAT_COL_ATIME,
    FSTAT_COL_MTIME,
    FSTAT_COL_CTIME,
    FSTAT_COL_PATTERN,
};

struct fstat_table {
    static constexpr const char *CREATE_STMT = R"(
CREATE TABLE fstat (
    st_parent TEXT,
    st_name TEXT,
    st_dev INTEGER,
    st_ino INTEGER,
    st_type TEXT,
    st_mode INTEGER,
    st_nlink INTEGER,
    st_uid TEXT,
    st_user TEXT,
    st_gid TEXT,
    st_group TEXT,
    st_rdev INTEGER,
    st_size INTEGER,
    st_blksize INTEGER,
    st_blocks INTEGER,
    st_atime DATETIME,
    st_mtime DATETIME,
    st_ctime DATETIME,
    pattern TEXT HIDDEN
);
)";

    struct vtab {
        sqlite3_vtab base;

        operator sqlite3_vtab *() {
            return &this->base;
        };
    };

    struct cursor {
        sqlite3_vtab_cursor base;
        string c_pattern;
        static_root_mem<glob_t, globfree> c_glob;
        size_t c_path_index{0};
        struct stat c_stat;

        cursor(sqlite3_vtab *vt) : base({vt}) {
            memset(&this->c_stat, 0, sizeof(this->c_stat));
        };

        void load_stat() {
            while ((this->c_path_index < this->c_glob->gl_pathc) &&
                   lstat(this->c_glob->gl_pathv[this->c_path_index],
                         &this->c_stat) == -1) {
                this->c_path_index += 1;
            }
        };

        int next() {
            if (this->c_path_index < this->c_glob->gl_pathc) {
                this->c_path_index += 1;
                this->load_stat();
            }

            return SQLITE_OK;
        };

        int reset() {
            return SQLITE_OK;
        }

        int eof() {
            return this->c_path_index >= this->c_glob->gl_pathc;
        };

        int get_rowid(sqlite3_int64 &rowid_out) {
            rowid_out = this->c_path_index;

            return SQLITE_OK;
        };
    };

    int get_column(const cursor &vc, sqlite3_context *ctx, int col) {
        const char *path = vc.c_glob->gl_pathv[vc.c_path_index];
        char time_buf[32];

        switch (col) {
            case FSTAT_COL_PARENT: {
                const char *slash = strrchr(path, '/');

                if (slash == nullptr) {
                    sqlite3_result_text(ctx, ".", 1, SQLITE_STATIC);
                } else if (path[1] == '\0') {
                    sqlite3_result_text(ctx, "", 0, SQLITE_STATIC);
                } else {
                    sqlite3_result_text(ctx, path, slash - path + 1, SQLITE_TRANSIENT);
                }
                break;
            }
            case FSTAT_COL_NAME: {
                const char *slash = strrchr(path, '/');

                if (slash == nullptr) {
                    sqlite3_result_text(ctx, path, -1, SQLITE_TRANSIENT);
                } else {
                    sqlite3_result_text(ctx, slash + 1, -1, SQLITE_TRANSIENT);
                }
                break;
            }
            case FSTAT_COL_DEV:
                sqlite3_result_int(ctx, vc.c_stat.st_dev);
                break;
            case FSTAT_COL_INO:
                sqlite3_result_int64(ctx, vc.c_stat.st_ino);
                break;
            case FSTAT_COL_TYPE:
                if (S_ISREG(vc.c_stat.st_mode)) {
                    sqlite3_result_text(ctx, "reg", 3, SQLITE_STATIC);
                } else if (S_ISBLK(vc.c_stat.st_mode)) {
                    sqlite3_result_text(ctx, "blk", 3, SQLITE_STATIC);
                } else if (S_ISCHR(vc.c_stat.st_mode)) {
                    sqlite3_result_text(ctx, "chr", 3, SQLITE_STATIC);
                } else if (S_ISDIR(vc.c_stat.st_mode)) {
                    sqlite3_result_text(ctx, "dir", 3, SQLITE_STATIC);
                } else if (S_ISFIFO(vc.c_stat.st_mode)) {
                    sqlite3_result_text(ctx, "fifo", 4, SQLITE_STATIC);
                } else if (S_ISLNK(vc.c_stat.st_mode)) {
                    sqlite3_result_text(ctx, "lnk", 3, SQLITE_STATIC);
                } else if (S_ISSOCK(vc.c_stat.st_mode)) {
                    sqlite3_result_text(ctx, "sock", 3, SQLITE_STATIC);
                }
                break;
            case FSTAT_COL_MODE:
                sqlite3_result_int(ctx, vc.c_stat.st_mode & 0777);
                break;
            case FSTAT_COL_NLINK:
                sqlite3_result_int(ctx, vc.c_stat.st_nlink);
                break;
            case FSTAT_COL_UID:
                sqlite3_result_int(ctx, vc.c_stat.st_uid);
                break;
            case FSTAT_COL_USER: {
                struct passwd *pw = getpwuid(vc.c_stat.st_uid);

                if (pw != nullptr) {
                    sqlite3_result_text(ctx, pw->pw_name, -1, SQLITE_TRANSIENT);
                } else {
                    sqlite3_result_int(ctx, vc.c_stat.st_uid);
                }
                break;
            }
            case FSTAT_COL_GID:
                sqlite3_result_int(ctx, vc.c_stat.st_gid);
                break;
            case FSTAT_COL_GROUP: {
                struct group *gr = getgrgid(vc.c_stat.st_gid);

                if (gr != nullptr) {
                    sqlite3_result_text(ctx, gr->gr_name, -1, SQLITE_TRANSIENT);
                } else {
                    sqlite3_result_int(ctx, vc.c_stat.st_gid);
                }
                break;
            }
            case FSTAT_COL_RDEV:
                sqlite3_result_int(ctx, vc.c_stat.st_rdev);
                break;
            case FSTAT_COL_SIZE:
                sqlite3_result_int64(ctx, vc.c_stat.st_size);
                break;
            case FSTAT_COL_BLKSIZE:
                sqlite3_result_int(ctx, vc.c_stat.st_blksize);
                break;
            case FSTAT_COL_BLOCKS:
                sqlite3_result_int(ctx, vc.c_stat.st_blocks);
                break;
            case FSTAT_COL_ATIME:
                sql_strftime(time_buf, sizeof(time_buf), vc.c_stat.st_atime, 0);
                sqlite3_result_text(ctx, time_buf, -1, SQLITE_TRANSIENT);
                break;
            case FSTAT_COL_MTIME:
                sql_strftime(time_buf, sizeof(time_buf), vc.c_stat.st_mtime, 0);
                sqlite3_result_text(ctx, time_buf, -1, SQLITE_TRANSIENT);
                break;
            case FSTAT_COL_CTIME:
                sql_strftime(time_buf, sizeof(time_buf), vc.c_stat.st_ctime, 0);
                sqlite3_result_text(ctx, time_buf, -1, SQLITE_TRANSIENT);
                break;
            case FSTAT_COL_PATTERN:
                sqlite3_result_text(ctx,
                                    vc.c_pattern.c_str(),
                                    vc.c_pattern.length(),
                                    SQLITE_TRANSIENT);
                break;
        }

        return SQLITE_OK;
    }

#if 0
    int update_row(sqlite3_vtab *tab,
                   sqlite3_int64 &index,
                   const char *st_parent,
                   const char *st_name,
                   int64_t st_dev,
                   int64_t st_ino,
                   const char *st_type,
                   int64_t st_mode,
                   int64_t st_nlink,
                   int64_t st_uid,
                   const char *st_user,
                   int64_t st_gid,
                   const char *st_group,
                   int64_t st_rdev,
                   int64_t st_size,
                   int64_t st_blksize,
                   int64_t st_blocks,
                   const char *atime,
                   const char *mtime,
                   const char *ctime,
                   const char *pattern) {

    };
#endif
};

static int rcBestIndex(sqlite3_vtab *tab, sqlite3_index_info *pIdxInfo)
{
    vtab_index_constraints vic(pIdxInfo);
    vtab_index_usage viu(pIdxInfo);

    for (auto iter = vic.begin(); iter != vic.end(); ++iter) {
        if (iter->op != SQLITE_INDEX_CONSTRAINT_EQ) {
            continue;
        }

        switch (iter->iColumn) {
            case FSTAT_COL_PATTERN:
                viu.column_used(iter);
                break;
        }
    }

    viu.allocate_args(1);
    return SQLITE_OK;
}

static int rcFilter(sqlite3_vtab_cursor *pVtabCursor,
                    int idxNum, const char *idxStr,
                    int argc, sqlite3_value **argv)
{
    fstat_table::cursor *pCur = (fstat_table::cursor *)pVtabCursor;

    if (argc != 1) {
        pCur->c_pattern.clear();
        return SQLITE_OK;
    }

    const char *pattern = (const char *) sqlite3_value_text(argv[0]);
    pCur->c_pattern = pattern;
    switch (glob(pattern,
#ifdef GLOB_TILDE
                 GLOB_TILDE|
#endif
                 GLOB_ERR,
                 nullptr,
                 pCur->c_glob.inout())) {
        case GLOB_NOSPACE:
            pVtabCursor->pVtab->zErrMsg = sqlite3_mprintf(
                "No space to perform glob()");
            return SQLITE_ERROR;
        case GLOB_NOMATCH:
            return SQLITE_OK;
    }

    pCur->load_stat();

    return SQLITE_OK;
}

int register_fstat_vtab(sqlite3 *db)
{
    static vtab_module<tvt_no_update<fstat_table>> FSTAT_MODULE;

    int rc;

    FSTAT_MODULE.vm_module.xBestIndex = rcBestIndex;
    FSTAT_MODULE.vm_module.xFilter = rcFilter;

    rc = FSTAT_MODULE.create(db, "fstat");

    ensure(rc == SQLITE_OK);

    return rc;
}
