// Notes:
    // Memory allocated via the "new" keyword IS garbage collected. Handles are not. Close handles when you're done with them
    // Handles are closed when the plugin is unloaded, so if the lifetime of a handle is the plugin's lifetime, don't worry about closing it
    // The contents of ArrayList objects are lost on map transition / server restart. Any persistent data should be stored in a
        // key-value file OR in a database

    // Basically every string function will add a null terminator, so add `+ 1` to the end of any defined size string definition
    // It is possible to throw an error with the ThrowError function, but anything that would bother should probably disable the
        // plugin entirely, so SetFailState is better

    // Large local var allocations if done commonly should be made static. Increases baseline memory usage, but lowers time spent
        // allocating memory. That being said, don't bother unless it's actually a problem. Name checks should be relatively
        // infrequent, and everything else exponentially less frequent. Dropping a frame or 2 to allocate 2048 bytes of memory
        // every century shouldn't be the end of the world

    // The database should contain:
        // The string used to compile a regex pattern, sanitized to avoid sql injection attacks
        // The steamid of the admin who added a regex pattern
        // The time a regex pattern was added

        // In the future, this may change to include regex compilation flags, kick/ban modes, etc. . Depends on how many features
        // I want to cram into this given how fundamentally shitty SourcePawn as a language is. I'm not trying to keep track of 17
        // different arrays and make sure that the indicies between them never get out of date. Maybe enum structs will solve my
        // concerns, maybe not

#pragma newdecls required
#pragma semicolon 1

#include <sourcemod>
#include <regex>

public Plugin myinfo = {
    name            = "SM Name Blocker",
    description     = "A simple plugin to stop people with blacklisted names from joining a server",
    author          = "NW/RL",
    version         = "alpha-0.1",
    url             = "git.dabikers.online/smnameblocker"
};

#define HANDLE_SIZE (32)
// This exists because you can't sizeof() a Handle, but it IS specified to be a 32bit integer. This should also equal the size of
// any other methodmap or descendant of Handle (like Regex)

#define PATTERN_MAX_LEN (512 + 1) /* 512 chars + null terminator */

#define DATABASE_FAIL_MSG "Could not populate regex & pattern lists from database"

enum OperatingMode {
    OP_DISABLED,
    OP_KICK,
    OP_BAN,
    OP_TOOBIG
}

ArrayList regexlist;
ArrayList patternlist;
Database db;

ConVar gcvarOperMode;       static const char OPERMODENAME[]            = "nameblock_OperatingMode";            const OperatingMode DEFAULTOPERMODE = OP_KICK;
ConVar gcvarAdmCmdFlag;     static const char ADMCMDFLAGNAME[]          = "nameblock_AdminCommandFlag";         const int DEFAULTADMCMDFLAG = ADMFLAG_BAN;
ConVar gcvarRegexCompFlags; static const char REGEXCOMPFLAGSNAME[]      = "nameblock_RegexCompilationFlags";    const int DEFAULTREGEXCOMPFLAGS = (PCRE_CASELESS | PCRE_DOTALL | PCRE_EXTENDED | PCRE_UTF8);
ConVar gcvarAmdImmFlag;     static const char ADMINIMMUNITYFLAGNAME[]   = "nameblock_AdminImmunityFlag";        const int DEFAULTADMIMMFLAG = ADMFLAG_GENERIC;



// Logs and throws an error with the same message of upto 2048 characters
void logAndFail(const char[] format, any ...) {
    char buf[2048 + 1];
    VFormat(buf, sizeof(buf), format, 2);

    LogError(buf);
    SetFailState(buf);
}

// Concatenate arguments into a single buffer
int concatArgs(char[] buf, int maxbuflen, int maxarglen, int end, int start=1) {
    if(maxbuflen <= 0 || start < 0) return -1;

    char[] arg = new char[maxarglen];
    char[] tmp = new char[maxbuflen];

    GetCmdArg(start, tmp, maxarglen); // Priming the first argument to prevent weirdness
    for(int i = start + 1; i <= end; i++) {
        GetCmdArg(i, arg, maxarglen);
        Format(tmp, maxbuflen, "%s %s", tmp, arg);
    }

    return strcopy(buf, maxbuflen, tmp);
}

// Register a convar who's default value is an integer
int registerIntConVar(ConVar& cv, int defaultVal, const char[] name, const char[] desc) {
    char tmp[32]; // Consider this a byte array
    Format(tmp, sizeof(tmp), "%d", defaultVal);

    cv = CreateConVar(name, tmp, desc);
    if(cv == null) return -1;
    cv.IntValue = defaultVal;

    return 0;
}

// `registerIntConVar` wrapper. Calls `logAndFail` if the convar couldn't be registered
void xRegisterIntConVar(ConVar& cv, int defaultVal, const char[] name, const char[] desc) {
    if(registerIntConVar(cv, defaultVal, name, desc)) logAndFail("Could not register cvar \"%s\"", name);
}



public void OnAllPluginsLoaded() {
    if(loadFromDatabase()) logAndFail(DATABASE_FAIL_MSG);

    // Register convars
    xRegisterIntConVar(gcvarOperMode,        view_as<int>(DEFAULTOPERMODE),  OPERMODENAME,           "Operating mode (disabled, kick, ban, etc.)");
    xRegisterIntConVar(gcvarAdmCmdFlag,      DEFAULTADMCMDFLAG,              ADMCMDFLAGNAME,         "Admin flag to modify pattern list");
    xRegisterIntConVar(gcvarRegexCompFlags,  DEFAULTREGEXCOMPFLAGS,          REGEXCOMPFLAGSNAME,     "Regular expression compilation flags");
    xRegisterIntConVar(gcvarAmdImmFlag,      DEFAULTADMIMMFLAG,              ADMINIMMUNITYFLAGNAME,  "Admin immunity flag");

    AutoExecConfig(true, "nameblocker_cvars");

    // Register commands
    RegAdminCmd("nb_addpattern",    cmdRegisterPattern,    gcvarAdmCmdFlag.IntValue, "Add a regex pattern to the filter list");
    RegAdminCmd("nb_removepattern", cmdDeletePattern,      gcvarAdmCmdFlag.IntValue, "Remove a regex pattern from the filter list");
    RegAdminCmd("nb_modifypattern", cmdReplacePattern,     gcvarAdmCmdFlag.IntValue, "Replace an existing regex pattern with a new pattern");
    RegAdminCmd("nb_listpatterns",  cmdListPatterns,       gcvarAdmCmdFlag.IntValue, "List current regex patterns and their indicies");
}

public void OnConfigsExecuted() {
    // I'm not sure when this is executed in relation to when OnClientPostAdminCheck is. Sourcemod's API reference says it's ran
    // once after OnMapStart, but idk if "Map Start" is a sufficient enough game state for players to join

    // Let me illustrate my concern:
        // Server starts normally, plugin is working
        // Players join. Nothing weird happens because the plugin loaded everything before a player could have joined
        // Players/Server initiates a map change WHILE players are still connected. If OnMapStart is when players can start
            // connecting, and is before OnConfigsExecuted, the following scenarios could happen:

        // 1: OnMapStart fires, players may join
        // 2: Player joins. This fires OnClientPostAdminCheck
        // 3: OnClientPostAdminCheck fires checkName, which tries to querry the array lists
        // 4: ArrayLists are empty or null, causing unexpected behavior
            // 4.1: ArrayLists are empty, nothing major happens, but a player with an invalid name gets through. Not ideal, but
                // also not the end of the world
            // 4.2: ArrayLists are null, trying to use them causes a null pointer dereference, either crashing the plugin &/or
                // server, or resulting in some other undefined behavior for sourcemod to deal with

        // If OnMapStart doesn't let players join, or rather OnConfigsExecuted fires before players can join, then there's no
        // problem. Alternatively, I can write something to kick/retry players until OnConfigsExecuted fires

        // As of now, I will simply leave this as a note. No need to go making weird systems if they may not be necessary

    if(loadFromDatabase()) logAndFail(DATABASE_FAIL_MSG);

}

public void OnClientPostAdminCheck(int client) {
    checkName(client);

}

public void OnClientSettingsChanged(int client) {
    checkName(client);

}



public Action cmdRegisterPattern(int client, int args) {
    if(args < 2) {
        ReplyToCommand(client, "Error: missing regex pattern");
        return Plugin_Handled;
    }

    char pattern[PATTERN_MAX_LEN];
    if(concatArgs(pattern, sizeof(pattern), PATTERN_MAX_LEN, args) <= 0) {
        ReplyToCommand(client, "Error: could not get argument list");
        return Plugin_Handled;
    }

    if(modPattern(DBM_INSERT, regexlist.Length, pattern)) {
        ReplyToCommand(client, "Error: could not register pattern");
        return Plugin_Handled;
    }

    return Plugin_Handled;
}

public Action cmdDeletePattern(int client, int args) {
    if(args < 2) {
        ReplyToCommand(client, "Error: no pattern index given");
        return Plugin_Handled;
    }

    int index;
    if(!GetCmdArgIntEx(1, index)) {
        ReplyToCommand(client, "Error: index argument not numerical");
        return Plugin_Handled;
    }

    if(modPattern(DBM_DELETE, index)) {
        ReplyToCommand(client, "Error: could not remove pattern");
        return Plugin_Handled;
    }

    return Plugin_Handled;
}

public Action cmdReplacePattern(int client, int args) {
    if(args < 3) {
        ReplyToCommand(client, "Error: missing index, replacement pattern, or both");
        return Plugin_Handled;
    }

    int index;
    if(!GetCmdArgIntEx(1, index)) {
        ReplyToCommand(client, "Error: index argument not numerical");
        return Plugin_Handled;
    }

    char pattern[PATTERN_MAX_LEN];
    if(concatArgs(pattern, sizeof(pattern), PATTERN_MAX_LEN, args, 2) <= 0) {
        ReplyToCommand(client, "Error: could not get argument list");
        return Plugin_Handled;
    }

    if(modPattern(DBM_INSERT | DBM_DELETE, index, pattern)) {
        ReplyToCommand(client, "Error: could not remove pattern from list");
        return Plugin_Handled;
    }

    return Plugin_Handled;
}

public Action cmdListPatterns(int client, int args) {
    for(int i = 0; i < patternlist.Length; i++) {
        ReplyToCommand(client, "[%d] %s", i, patternlist.Get(i));
    }

    return Plugin_Handled;
}



int aInsertPattern(char pattern[PATTERN_MAX_LEN], Regex res, int index) {
    if(IsNullString(pattern) || index < 0 || index > regexlist.Length) return -1;

    if(index == regexlist.Length) {
        regexlist.Push(res);
        patternlist.Push(pattern);

    } else {
        regexlist.ShiftUp(index);
        patternlist.ShiftUp(index);
        regexlist.Set(index, res);
        patternlist.Set(index, pattern);

    }

    return 0;
}

int aRemovePattern(int index) {
    if(index < 0 || index >= regexlist.Length) return -1;

    regexlist.Erase(index);
    patternlist.Erase(index);

    return 0;
}

enum DBMOD_MODE {
    DBM_UNDEF,
    DBM_INSERT = (1<<0),
    DBM_DELETE = (1<<1),
    DBM_TOOBIG
};

int modPattern(DBMOD_MODE mode, int index, char[] pattern="") {
    if(index < 0 || index > regexlist.Length) return -1;
    if(mode <= DBM_UNDEF || mode >= DBM_TOOBIG) return -1;

    Transaction modification = SQL_CreateTransaction();
    if(modification == null) return -1;

    // char errstr[512]; RegexError reerr;
    // Regex res = CompileRegex(pattern, gcvarRegexCompFlags.IntValue, errstr, sizeof(errstr), reerr);
    // if(res == null) {
    //     LogError("Error: Could not compile regex pattern \"%s\": %s (%d)", pattern, errstr, reerr);
    //     return -1;
    // }

    // Update transaction
    // Update lists
        // Try to delete before inserting

    return 0;
}

int loadFromDatabase() {
    logAndFail("function \"loadFromDatabase\" not implemented");

    // Get database handle
    char sqlerr[256 + 1];
    db = SQLite_UseDatabase("sourcemod-local", sqlerr, sizeof(sqlerr));
    if(db == null) logAndFail("Could not connect to sql database: %s", sqlerr);

    // Initialize table if it doesn't exist


    // Initialize and populate datatypes
    regexlist = new ArrayList(ByteCountToCells(HANDLE_SIZE));
    if(regexlist == null) logAndFail("Could not initialize regexlist ArrayList");

    patternlist = new ArrayList(ByteCountToCells(PATTERN_MAX_LEN));
    if(patternlist == null) logAndFail("Could not initialize patternlist ArrayList");

    // select patterns from nameblock table/database
    // compile each pattern
    // insert pattern & regex into respective lists

    return 0;
}



// Check's a user's name against the regex list. Returns -1 on error, 0 if skipped, 1 on hit
int checkName(int client) {
    if(client <= 0) return 0;
    if(gcvarOperMode.IntValue == view_as<int>(OP_DISABLED)) return 0;
    if(CheckCommandAccess(client, "", gcvarAmdImmFlag.IntValue, true)) return 0;

    char name[64 + 1];
    if(getName(client, name, sizeof(name)) <= 0) {
        LogError("Tried to get a client's name for a name check, but could not");
        return -1;
    }

    RegexError reerr;
    for(int i = 0, m = 0; i < regexlist.Length; i++) {
        m = MatchRegex(regexlist.Get(i), name, reerr);

        if(m < 0) {
            handleFailedRegex(client, reerr);
            return -1;
        }
        if(m == 0) continue;

        handleNameHit(client);
        break;
    }

    return 1;
}

int getName(int client, char[] buf, int buflen) {
    if(client <= 0 || buflen <= 0) return -1;
    if(IsNullString(buf)) return -1;

    return Format(buf, buflen, "%N", client);
}

int handleNameHit(int client) {
    if(client <= 0) return -1;

    switch(gcvarOperMode.IntValue) {
        case OP_DISABLED: {return 0;}
        case OP_KICK: {
            KickClient(client, "Failed name check");
            LogAction(0, client, "Kicked %L for failing a name check", client);
            return 0;
        }
        case OP_BAN: {
            // BanClient()
            // TODO: Interop with other ban systems
            // Log ban
        }
        default: {
            LogError("%L failed a name check, but the operating mode in an invalid state", client);
            return -1;
        }
    }

    LogError("Broke out of switch statement that shouldn't have happened");
    return -1; // Shouldn't get to this point
}

int handleFailedRegex(int client, RegexError reerr) {
    char regstr[128];
    RegexStrError(reerr, regstr, sizeof(regstr));

    LogError("Ran into regex error when trying to check user %L's name. Reported regex error: %s", client, regstr);
    return 0;
}



// Note: May or may not be particularly descriptive for any given error
int RegexStrError(RegexError err, char[] buf, int buflen) {
    if(IsNullString(buf)) return -1;

    char tmp[64];
    switch(err) {
        case REGEX_ERROR_NONE: {tmp = "No error";}

        case REGEX_ERROR_ASSERT:    {tmp = "Internal error";}
        case REGEX_ERROR_BADBR:     {tmp = "Invalid repeat counts in {}";}
        case REGEX_ERROR_BADPAT:    {tmp = "Pattern error";}
        case REGEX_ERROR_BADRPT:    {tmp = "? * + invalid";}
        case REGEX_ERROR_EBRACE:    {tmp = "Unbalanced {}";}
        case REGEX_ERROR_EBRACK:    {tmp = "Unbalanced []";}
        case REGEX_ERROR_ECOLLATE:  {tmp = "Collation error - not relevant";}
        case REGEX_ERROR_ECTYPE:    {tmp = "Bad class";}
        case REGEX_ERROR_EESCAPE:   {tmp = "Bad escape sequence";}
        case REGEX_ERROR_EMPTY:     {tmp = "Empty expression";}
        case REGEX_ERROR_EPAREN:    {tmp = "Unbalanced ()";}
        case REGEX_ERROR_ERANGE:    {tmp = "Bad range inside []";}
        case REGEX_ERROR_ESIZE:     {tmp = "Expression too big";}
        case REGEX_ERROR_ESPACE:    {tmp = "Failed to get memory";}
        case REGEX_ERROR_ESUBREG:   {tmp = "Bad back reference";}
        case REGEX_ERROR_INVARG:    {tmp = "Bad argument";}

        case REGEX_ERROR_NOMATCH:           {tmp = "No match was found";}
        case REGEX_ERROR_NULL:              {tmp = "Null";}
        case REGEX_ERROR_BADOPTION:         {tmp = "Bad Option";}
        case REGEX_ERROR_BADMAGIC:          {tmp = "Bad Magic";}
        case REGEX_ERROR_UNKNOWN_OPCODE:    {tmp = "Unknown OpCode";}
        case REGEX_ERROR_NOMEMORY:          {tmp = "No Memory";}
        case REGEX_ERROR_NOSUBSTRING:       {tmp = "No substring";}
        case REGEX_ERROR_MATCHLIMIT:        {tmp = "Match limit";}
        case REGEX_ERROR_CALLOUT:           {tmp = "Callout";} // Never used by PCRE itself
        case REGEX_ERROR_BADUTF8:           {tmp = "Bad UTF8";}
        case REGEX_ERROR_BADUTF8_OFFSET:    {tmp = "Bad UTF8 offset";}
        case REGEX_ERROR_PARTIAL:           {tmp = "Partial";}
        case REGEX_ERROR_BADPARTIAL:        {tmp = "Bad Partial";}
        case REGEX_ERROR_INTERNAL:          {tmp = "Internal error";}
        case REGEX_ERROR_BADCOUNT:          {tmp = "Bad count";}
        case REGEX_ERROR_DFA_UITEM:         {tmp = "DFA UItem";}
        case REGEX_ERROR_DFA_UCOND:         {tmp = "DFA UCOND";}
        case REGEX_ERROR_DFA_UMLIMIT:       {tmp = "DFA UMLIMIT";}
        case REGEX_ERROR_DFA_WSSIZE:        {tmp = "DFA WSSIZE";}
        case REGEX_ERROR_DFA_RECURSE:       {tmp = "DFA recurse";}
        case REGEX_ERROR_RECURSIONLIMIT:    {tmp = "Recursion Limit";}
        case REGEX_ERROR_NULLWSLIMIT:       {tmp = "NULL WSLIMIT";}  /* No longer actually used */
        case REGEX_ERROR_BADNEWLINE:        {tmp = "Bad newline";}
        case REGEX_ERROR_BADOFFSET:         {tmp = "Bad offset";}
        case REGEX_ERROR_SHORTUTF8:         {tmp = "Short UFT8";}
        case REGEX_ERROR_RECURSELOOP:       {tmp = "Recurse loop";}
        case REGEX_ERROR_JIT_STACKLIMIT:    {tmp = "JIT Stacklimit";}
        case REGEX_ERROR_BADMODE:           {tmp = "Bad mode";}
        case REGEX_ERROR_BADENDIANNESS:     {tmp = "Bad endianness";}
        case REGEX_ERROR_DFA_BADRESTART:    {tmp = "DFA Bad Restart";}
        case REGEX_ERROR_JIT_BADOPTION:     {tmp = "JIT bad option";}
        case REGEX_ERROR_BADLENGTH:         {tmp = "Bad length";}

        default: {tmp = "Unknown Error";}
    }

    return strcopy(buf, buflen, tmp);
}