#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include "error_numbers.h"
#include "util.h"
#include "db_base.h"

#define MAX_QUERY_LEN 256000
    // TODO: use "string" instead of char[]

DB_CONN::DB_CONN() {
    mysql = 0;
}

int DB_CONN::open(char* db_name, char* db_host, char* db_user, char* dbpassword) {
    mysql = mysql_init(0);
    if (!mysql) return ERR_DB_CANT_INIT;
    mysql = mysql_real_connect(mysql, db_host, db_user, dbpassword, db_name, 0, 0, 0);
    if (mysql == 0) return ERR_DB_CANT_CONNECT;
    return 0;
}

void DB_CONN::close() {
    if (mysql) mysql_close(mysql);
}

int DB_CONN::do_query(char* p) {
    int retval;
    retval = mysql_query(mysql, p);
    if (retval) {
        fprintf(stderr, "Database error: query=%s\n", p);
    }
    return retval;
}

int DB_CONN::insert_id() {
    int retval;
    MYSQL_ROW row;
    MYSQL_RES* rp;
            
    retval = do_query("select LAST_INSERT_ID()");
    if (retval) return retval;
    rp = mysql_store_result(mysql);
    row = mysql_fetch_row(rp);
    return atoi(row[0]);
}

void DB_CONN::print_error(char* p) {
    if (mysql) {
        fprintf(stderr, "%s: Database error: %s\n", p, mysql_error(mysql));
    } else {
        fprintf(stderr, "%s: Database error\n", p);
    }
}

const char* DB_CONN::error_string() {
    return mysql?mysql_error(mysql):"Not connected";
}

DB_BASE::DB_BASE(DB_CONN& p, char *tn) : db(&p), table_name(tn) {
    cursor.active = false;
}

int DB_BASE::get_id() { return 0;}
void DB_BASE::db_print(char*) {}

void DB_BASE::db_parse(MYSQL_ROW&) {}

int DB_BASE::insert() {
    char vals[MAX_QUERY_LEN], query[MAX_QUERY_LEN];
    db_print(vals);
    sprintf(query, "insert into %s set %s", table_name, vals);
    return db->do_query(query);
}

// update an entire record
//
int DB_BASE::update() {
    char vals[MAX_QUERY_LEN], query[MAX_QUERY_LEN];
    db_print(vals);
    sprintf(query, "update %s set %s where id=%d", table_name, vals, get_id());
    return db->do_query(query);
}

// update one or more fields
// "clause" is something like "foo=5, blah='xxx'" or "foo=foo+5"
//
int DB_BASE::update_field(char* clause) {
    char query[MAX_QUERY_LEN];
    sprintf(query, "update %s set %s where id=%d", table_name, clause, get_id());
    return db->do_query(query);
}

int DB_BASE::lookup(char* clause) {
    char query[MAX_QUERY_LEN];
    int retval;
    MYSQL_ROW row;
    MYSQL_RES* rp;

    sprintf(query, "select * from %s %s", table_name, clause);
    retval = db->do_query(query);
    if (retval) return retval;
    rp = mysql_store_result(db->mysql);
    if (!rp) return -1;
    row = mysql_fetch_row(rp);
    if (row) db_parse(row);
    mysql_free_result(rp);
    if (row == 0) return ERR_DB_NOT_FOUND;

    // make sure there's exactly one row
    //
    row = mysql_fetch_row(rp);
    if (row) return ERR_DB_NOT_UNIQUE;
    return 0;
}

int DB_BASE::lookup_id(int id) {
    char query[MAX_QUERY_LEN];
    int retval;
    MYSQL_ROW row;
    MYSQL_RES* rp;

    sprintf(query, "select * from %s where id=%d", table_name, id);
    retval = db->do_query(query);
    if (retval) return retval;
    rp = mysql_store_result(db->mysql);
    if (!rp) return -1;
    row = mysql_fetch_row(rp);
    if (row) db_parse(row);
    mysql_free_result(rp);
    if (row == 0) return ERR_DB_NOT_FOUND;

    // don't bother checking for uniqueness here
    return 0;
}

int DB_BASE::enumerate(char* clause) {
    int x;
    char query[MAX_QUERY_LEN];
    MYSQL_ROW row;

    if (!cursor.active) {
        cursor.active = true;
        sprintf(query, "select * from %s %s", table_name, clause);
        x = db->do_query(query);
        if (x) return mysql_errno(db->mysql);
        cursor.rp = mysql_store_result(db->mysql);
        if (!cursor.rp) return mysql_errno(db->mysql);
    }
    row = mysql_fetch_row(cursor.rp);
    if (!row) {
        mysql_free_result(cursor.rp);
        cursor.active = false;
        return 1;
    } else {
        db_parse(row);
    }
    return 0;
}

int DB_BASE::get_integer(char* query, int& n) {
    int retval;
    MYSQL_ROW row;
    MYSQL_RES* resp;

    retval = db->do_query(query);
    if (retval) return retval;
    resp = mysql_store_result(db->mysql);
    if (!resp) return ERR_DB_NOT_FOUND;
    row = mysql_fetch_row(resp);
    if (!row) return ERR_DB_NOT_FOUND;
    if (!row[0]) return ERR_DB_NOT_FOUND;
    n = atoi(row[0]);
    mysql_free_result(resp);
    return 0;
}

int DB_BASE::get_double(char* query, double& x) {
    int retval;
    MYSQL_ROW row;
    MYSQL_RES* resp;

    retval = db->do_query(query);
    if (retval) return retval;
    resp = mysql_store_result(db->mysql);
    if (!resp) return ERR_DB_NOT_FOUND;
    row = mysql_fetch_row(resp);
    if (!row) return ERR_DB_NOT_FOUND;
    if (!row[0]) return ERR_DB_NOT_FOUND;
    x = atof(row[0]);
    mysql_free_result(resp);
    return 0;
}

int DB_BASE::count(int& n, char* clause) {
    char query[MAX_QUERY_LEN];
    sprintf(query, "select count(*) from %s %s", table_name, clause);
    return get_integer(query, n);
}

int DB_BASE::sum(double& x, char* field, char* clause) {
    char query[MAX_QUERY_LEN];
    sprintf(query, "select sum(%s) from %s %s", field, table_name, clause);
    return get_double(query, x);
}

// convert a string into a form that allows it to be used
// in SQL queries delimited by single quotes:
// replace ' with \', \ with \\
//
void escape_string(char* field, int len) {
    char buf[MAX_QUERY_LEN];
    char* q = buf, *p = field;
    while (*p) {
        if (*p == '\'') {
            *q++ = '\\';
            *q++ = '\'';
        } else if (*p == '\\') {
            *q++ = '\\';
            *q++ = '\\';
        } else {
            *q++ = *p;
        }
        p++;
    }
    *q = 0;
    safe_strncpy(field, buf, len);
}

// undo the above process
// (len not used because this doesn't expand the string)
//
void unescape_string(char* p, int /*len*/) {
    while (*p) {
        if (*p == '\\') {
            strcpy(p, p+1);
        }
        p++;
    }
}