/++
	Implementation of the [arsd.database.Database] interface for
	accessing MySQL (and MariaDB) databases. Uses the official MySQL client
	library, and thus needs that installed to compile and run.

	$(PITFALL
		If you're using MySQL client library v5.0 or less,
		you must pass this to dmd: `-version=Less_Than_MySQL_51`
		This is important - otherwise you will see bizarre segfaults!
	)
+/
module arsd.mysql;


//version(MySQL_51) {
	// we good
/*} else*/ version(Less_Than_MySQL_51) {
	// we good
} else {
	// default now is mysql 5.1 or up - it has been long
	// enough that surely most everyone uses it and we don't
	// need the pragma warning anymore. Of course, the old is
	// still available if you need to explicitly opt in.
	version = MySQL_51;
}

version(Windows) {
	pragma(lib, "libmysql");
}
else {
	pragma(lib, "mysqlclient");
}

public import arsd.database;

import std.stdio;
import std.exception;
import std.string;
import std.conv;
import std.typecons;
import core.stdc.config;

/++
	Represents a query result. You can loop over this with a
	`foreach` statement to access individual [Row|rows].

	[Row]s expose both an index and associative array interface,
	so you can get `row[0]` for the first item, or `row["name"]`
	to get a column by name from the result set.
+/
class MySqlResult : ResultSet {
	private int[string] mapping;
	private MYSQL_RES* result;

	private int itemsTotal;
	private int itemsUsed;

	string sql;

	this(MYSQL_RES* r, string sql) {
		result = r;
		itemsTotal = cast(int) length();
		itemsUsed = 0;

		this.sql = sql;

		// prime it
		if(itemsTotal)
			fetchNext();
	}

	~this() {
		if(result !is null)
			mysql_free_result(result);
	}


	MYSQL_FIELD[] fields() {
		int numFields = mysql_num_fields(result);
		auto fields = mysql_fetch_fields(result);

		MYSQL_FIELD[] ret;
		for(int i = 0; i < numFields; i++) {
			ret ~= fields[i];
		}

		return ret;
	}


	/// The number of returned rows
	override size_t length() {
		if(result is null)
			return 0;
		return cast(int) mysql_num_rows(result);
	}

	/// Range primitive used by `foreach`
	/// You may also use this to check if there was any result.
	override bool empty() {
		return itemsUsed == itemsTotal;
	}

	/// Range primitive used by `foreach`
	override Row front() {
		return row;
	}

	/// Range primitive used by `foreach`
	override void popFront() {
		itemsUsed++;
		if(itemsUsed < itemsTotal) {
			fetchNext();
		}
	}

	override int getFieldIndex(string field) {
		if(mapping is null)
			makeFieldMapping();
		debug {
			if(field !in mapping)
				throw new Exception(field ~ " not in result");
		}
		return mapping[field];
	}

	private void makeFieldMapping() {
		int numFields = mysql_num_fields(result);
		auto fields = mysql_fetch_fields(result);

		if(fields is null)
			return;

		for(int i = 0; i < numFields; i++) {
			if(fields[i].name !is null)
				mapping[fromCstring(fields[i].name, fields[i].name_length)] = i;
		}
	}

	private void fetchNext() {
		assert(result);
		auto r = mysql_fetch_row(result);
		if(r is null)
			throw new Exception("there is no next row");
		uint numFields = mysql_num_fields(result);
		auto lengths = mysql_fetch_lengths(result);
		string[] row;
		// potential FIXME: not really binary safe

		columnIsNull.length = numFields;
		for(int a = 0; a < numFields; a++) {
			if(*(r+a) is null) {
				row ~= null;
				columnIsNull[a] = true;
			} else {
				row ~= fromCstring(*(r+a), *(lengths + a));
				columnIsNull[a] = false;
			}
		}

		this.row.row = row;
		this.row.resultSet = this;
	}


	override string[] fieldNames() {
		int numFields = mysql_num_fields(result);
		auto fields = mysql_fetch_fields(result);

		string[] names;
		for(int i = 0; i < numFields; i++) {
			names ~= fromCstring(fields[i].name, fields[i].name_length);
		}

		return names;
	}



	bool[] columnIsNull;
	Row row;
}

/++
	The main class for accessing the MySql database.

	---
		// connect to database with the constructor
		auto db = new MySql("localhost", "my_user", "my_password", "my_database_name");
		// use the query function to execute sql...
		// use ? for data placeholders...
		db.query("INSERT INTO people (id, name) VALUES (?, ?)", 10, "My Name");
		// and use foreach to loop over result sets
		foreach(row; db.query("SELECT id, name FROM people ORDER BY name LIMIT 10"))
			writeln(row[0], " ", row["name"]); // index and name supported
	---
+/
class MySql : Database {
	this(string host, string user, string pass, string db, uint port = 0) {
		mysql = enforce!(DatabaseException)(
			mysql_init(null),
			"Couldn't init mysql");
		enforce!(DatabaseException)(
			mysql_real_connect(mysql, toCstring(host), toCstring(user), toCstring(pass), toCstring(db), port, null, 0),
			error());

		dbname = db;

		// we want UTF8 for everything

		query("SET NAMES 'utf8'");
		//query("SET CHARACTER SET utf8");
	}

	string dbname;

	///
	override void startTransaction() {
		query("START TRANSACTION");
	}


	string sysTimeToValue(SysTime s) {
		return "cast('" ~ escape(s.toISOExtString()) ~ "' as datetime)";
	}

	string error() {
		return fromCstring(mysql_error(mysql));
	}

	void close() {
		mysql_close(mysql);
	}

	~this() {
		close();
	}

	///
	int lastInsertId() {
		return cast(int) mysql_insert_id(mysql);
	}



	/// Builds and executes an INERT INTO statement
	int insert(string table, MySqlResult result, string[string] columnsToModify, string[] columnsToSkip) {
		assert(!result.empty);
		string sql = "INSERT INTO `" ~ table ~ "` ";

		string cols = "(";
		string vals = "(";
		bool outputted = false;

		string[string] columns;
		auto cnames = result.fieldNames;
		foreach(i, col; result.front.toStringArray) {
			bool skipMe = false;
			foreach(skip; columnsToSkip) {
				if(cnames[i] == skip) {
					skipMe = true;
					break;
				}
			}
			if(skipMe)
				continue;

			if(outputted) {
				cols ~= ",";
				vals ~= ",";
			} else
				outputted = true;

			cols ~= cnames[i];

			if(result.columnIsNull[i] && cnames[i] !in columnsToModify)
				vals ~= "NULL";
			else {
				string v = col;
				if(cnames[i] in columnsToModify)
					v = columnsToModify[cnames[i]];

				vals ~= "'" ~ escape(v) ~ "'"; 

			}
		}

		cols ~= ")";
		vals ~= ")";

		sql ~= cols ~ " VALUES " ~ vals;

		query(sql);

		result.popFront;

		return lastInsertId;
	}

	string escape(string str) {
		ubyte[] buffer = new ubyte[str.length * 2 + 1];
		buffer.length = mysql_real_escape_string(mysql, buffer.ptr, cast(cstring) str.ptr, cast(uint) str.length);

		return cast(string) buffer;
	}

	string escaped(T...)(string sql, T t) {
		static if(t.length > 0) {
			string fixedup;
			int pos = 0;


			void escAndAdd(string str, int q) {
				ubyte[] buffer = new ubyte[str.length * 2 + 1];
				buffer.length = mysql_real_escape_string(mysql, buffer.ptr, cast(cstring) str.ptr, str.length);

				fixedup ~= sql[pos..q] ~ '\'' ~ cast(string) buffer ~ '\'';

			}

			foreach(a; t) {
				int q = sql[pos..$].indexOf("?");
				if(q == -1)
					break;
				q += pos;

				static if(__traits(compiles, t is null)) {
					if(t is null)
						fixedup  ~= sql[pos..q] ~ "NULL";
					else
						escAndAdd(to!string(*a), q);
				} else {
					string str = to!string(a);
					escAndAdd(str, q);
				}

				pos = q+1;
			}

			fixedup ~= sql[pos..$];

			sql = fixedup;

			//writefln("\n\nExecuting sql: %s", sql);
		}

		return sql;
	}


	/// Gets a minimal ORM object from a query
	ResultByDataObject!R queryDataObject(R = DataObject, T...)(string sql, T t) {
		// modify sql for the best data object grabbing
		sql = fixupSqlForDataObjectUse(sql);

		auto magic = query(sql, t);
		return ResultByDataObject!R(cast(MySqlResult) magic, this);
	}


	/// ditto
	ResultByDataObject!R queryDataObjectWithCustomKeys(R = DataObject, T...)(string[string] keyMapping, string sql, T t) {
		sql = fixupSqlForDataObjectUse(sql, keyMapping);

		auto magic = query(sql, t);
		return ResultByDataObject!R(cast(MySqlResult) magic, this);
	}



	///
	int affectedRows() {
		return cast(int) mysql_affected_rows(mysql);
	}

	override ResultSet queryImpl(string sql, Variant[] args...) {
		sql = escapedVariants(this, sql, args);

		enforce!(DatabaseException)(
			!mysql_query(mysql, toCstring(sql)),
		error() ~ " :::: " ~ sql);

		return new MySqlResult(mysql_store_result(mysql), sql);
	}
/+
	Result queryOld(T...)(string sql, T t) {
		sql = escaped(sql, t);

		if(sql.length == 0)
			throw new DatabaseException("empty query");
		/*
		static int queryCount = 0;
		queryCount++;
		if(sql.indexOf("INSERT") != -1)
			stderr.writefln("%d: %s", queryCount, sql.replace("\n", " ").replace("\t", ""));
		*/

		version(dryRun) {
			pragma(msg, "This is a dry run compile, no queries will be run");
			writeln(sql);
			return Result(null, null);
		}

		enforceEx!(DatabaseException)(
			!mysql_query(mysql, toCstring(sql)),
		error() ~ " :::: " ~ sql);

		return Result(mysql_store_result(mysql), sql);
	}
+/
/+
	struct ResultByAssoc {
		this(Result* r) {
			result = r;
			fields = r.fieldNames();
		}

		ulong length() { return result.length; }
		bool empty() { return result.empty; }
		void popFront() { result.popFront(); }
		string[string] front() {
			auto r = result.front;
			string[string] ret;
			foreach(i, a; r) {
				ret[fields[i]] = a;
			}

			return ret;
		}

		@disable this(this) { }

		string[] fields;
		Result* result;
	}


	struct ResultByStruct(T) {
		this(Result* r) {
			result = r;
			fields = r.fieldNames();
		}

		ulong length() { return result.length; }
		bool empty() { return result.empty; }
		void popFront() { result.popFront(); }
		T front() {
			auto r = result.front;
			string[string] ret;
			foreach(i, a; r) {
				ret[fields[i]] = a;
			}

			T s;
			// FIXME: should use tupleOf
			foreach(member; s.tupleof) {
				if(member.stringof in ret)
					member = to!(typeof(member))(ret[member]);
			}

			return s;
		}

		@disable this(this) { }

		string[] fields;
		Result* result;
	}
+/

/+


	struct Result {
		private Result* heaped() {
			auto r = new Result(result, sql, false);

			r.tupleof = this.tupleof;

			this.itemsTotal = 0;
			this.result = null;

			return r;
		}

		this(MYSQL_RES* r, string sql, bool prime = true) {
			result = r;
			itemsTotal = length;
			itemsUsed = 0;
			this.sql = sql;
			// prime it here
			if(prime && itemsTotal)
				fetchNext();
		}

		string sql;

		~this() {
			if(result !is null)
			mysql_free_result(result);
		}

		/+
		string[string][] fetchAssoc() {

		}
		+/

		ResultByAssoc byAssoc() {
			return ResultByAssoc(&this);
		}

		ResultByStruct!(T) byStruct(T)() {
			return ResultByStruct!(T)(&this);
		}

		string[] fieldNames() {
			int numFields = mysql_num_fields(result);
			auto fields = mysql_fetch_fields(result);

			string[] names;
			for(int i = 0; i < numFields; i++) {
				names ~= fromCstring(fields[i].name);
			}

			return names;
		}

		MYSQL_FIELD[] fields() {
			int numFields = mysql_num_fields(result);
			auto fields = mysql_fetch_fields(result);

			MYSQL_FIELD[] ret;
			for(int i = 0; i < numFields; i++) {
				ret ~= fields[i];
			}

			return ret;
		}

		ulong length() {
			if(result is null)
				return 0;
			return mysql_num_rows(result);
		}

		bool empty() {
			return itemsUsed == itemsTotal;
		}

		Row front() {
			return row;
		}

		void popFront() {
			itemsUsed++;
			if(itemsUsed < itemsTotal) {
				fetchNext();
			}
		}

		void fetchNext() {
			auto r = mysql_fetch_row(result);
			uint numFields = mysql_num_fields(result);
			uint* lengths = mysql_fetch_lengths(result);
			row.length = 0;
			// potential FIXME: not really binary safe

			columnIsNull.length = numFields;
			for(int a = 0; a < numFields; a++) {
				if(*(r+a) is null) {
					row ~= null;
					columnIsNull[a] = true;
				} else {
					row ~= fromCstring(*(r+a), *(lengths + a));
					columnIsNull[a] = false;
				}
			}
		}

		@disable this(this) {}
		private MYSQL_RES* result;

		ulong itemsTotal;
		ulong itemsUsed;
		
		alias string[] Row;

		Row row;
		bool[] columnIsNull; // FIXME: should be part of the row
	}
+/
  private:
	MYSQL* mysql;
}

struct ResultByDataObject(ObjType) if (is(ObjType : DataObject)) {
	this(MySqlResult r, MySql mysql) {
		result = r;
		auto fields = r.fields();
		this.mysql = mysql;

		foreach(i, f; fields) {
			string tbl = fromCstring(f.org_table is null ? f.table : f.org_table, f.org_table is null ? f.table_length : f.org_table_length);
			mappings[fromCstring(f.name)] = tuple(
					tbl,
					fromCstring(f.org_name is null ? f.name : f.org_name, f.org_name is null ? f.name_length : f.org_name_length));
		}


	}

	Tuple!(string, string)[string] mappings;

	ulong length() { return result.length; }
	bool empty() { return result.empty; }
	void popFront() { result.popFront(); }
	ObjType front() {
		return new ObjType(mysql, result.front.toAA, mappings);
	}
	// would it be good to add a new() method? would be valid even if empty
	// it'd just fill in the ID's at random and allow you to do the rest

	@disable this(this) { }

	MySqlResult result;
	MySql mysql;
}

extern(System) {
	struct MYSQL;
	struct MYSQL_RES;
	/* typedef */ alias const(ubyte)* cstring;

	struct MYSQL_FIELD {
		  cstring name;                 /* Name of column */
		  cstring org_name;             /* Original column name, if an alias */ 
		  cstring table;                /* Table of column if column was a field */
		  cstring org_table;            /* Org table name, if table was an alias */
		  cstring db;                   /* Database for table */
		  cstring catalog;	      /* Catalog for table */
		  cstring def;                  /* Default value (set by mysql_list_fields) */
		  c_ulong length;       /* Width of column (create length) */
		  c_ulong max_length;   /* Max width for selected set */
		  uint name_length;
		  uint org_name_length;
		  uint table_length;
		  uint org_table_length;
		  uint db_length;
		  uint catalog_length;
		  uint def_length;
		  uint flags;         /* Div flags */
		  uint decimals;      /* Number of decimals in field */
		  uint charsetnr;     /* Character set */
		  uint type; /* Type of field. See mysql_com.h for types */
		  // type is actually an enum btw
		  
		version(MySQL_51) {
			void* extension;
		}
	}

	/* typedef */ alias cstring* MYSQL_ROW;

	cstring mysql_get_client_info();
	MYSQL* mysql_init(MYSQL*);
	uint mysql_errno(MYSQL*);
	cstring mysql_error(MYSQL*);

	MYSQL* mysql_real_connect(MYSQL*, cstring, cstring, cstring, cstring, uint, cstring, c_ulong);

	int mysql_query(MYSQL*, cstring);

	void mysql_close(MYSQL*);

	ulong mysql_num_rows(MYSQL_RES*);
	uint mysql_num_fields(MYSQL_RES*);
	bool mysql_eof(MYSQL_RES*);

	ulong mysql_affected_rows(MYSQL*);
	ulong mysql_insert_id(MYSQL*);

	MYSQL_RES* mysql_store_result(MYSQL*);
	MYSQL_RES* mysql_use_result(MYSQL*);

	MYSQL_ROW mysql_fetch_row(MYSQL_RES *);
	c_ulong* mysql_fetch_lengths(MYSQL_RES*);
	MYSQL_FIELD* mysql_fetch_field(MYSQL_RES*);
	MYSQL_FIELD* mysql_fetch_fields(MYSQL_RES*);

	uint mysql_real_escape_string(MYSQL*, ubyte* to, cstring from, c_ulong length);

	void mysql_free_result(MYSQL_RES*);

}

import std.string;
cstring toCstring(string c) {
	return cast(cstring) toStringz(c);
}

import std.array;
string fromCstring(cstring c, size_t len = size_t.max) {
	string ret;
	if(c is null)
		return null;
	if(len == 0)
		return "";
	if(len == size_t.max) {
		auto iterator = c;
		len = 0;
		while(*iterator) {
			iterator++;
			len++;
		}
		assert(len >= 0);
	}

	ret = cast(string) (c[0 .. len].idup);

	return ret;
}


// FIXME: this should work generically with all database types and them moved to database.d
///
Ret queryOneRow(Ret = Row, DB, string file = __FILE__, size_t line = __LINE__, T...)(DB db, string sql, T t) if(
	(is(DB : Database))
	// && (is(Ret == Row) || is(Ret : DataObject)))
	)
{
	static if(is(Ret : DataObject) && is(DB == MySql)) {
		auto res = db.queryDataObject!Ret(sql, t);
		if(res.empty)
			throw new EmptyResultException("result was empty", file, line);
		return res.front;
	} else static if(is(Ret == Row)) {
		auto res = db.query(sql, t);
		if(res.empty)
			throw new EmptyResultException("result was empty", file, line);
		return res.front;
	} else static assert(0, "Unsupported single row query return value, " ~ Ret.stringof);
}

///
class EmptyResultException : Exception {
	this(string message, string file = __FILE__, size_t line = __LINE__) {
		super(message, file, line);
	}
}


/*
void main() {
	auto mysql = new MySql("localhost", "uname", "password", "test");
	scope(exit) delete mysql;

	mysql.query("INSERT INTO users (id, password) VALUES (?, ?)", 10, "lol");

	foreach(row; mysql.query("SELECT * FROM users")) {
		writefln("%s %s %s %s", row["id"], row[0], row[1], row["username"]);
	}
}
*/

/*
struct ResultByStruct(T) {
	this(MySql.Result* r) {
		result = r;
		fields = r.fieldNames();
	}

	ulong length() { return result.length; }
	bool empty() { return result.empty; }
	void popFront() { result.popFront(); }
	T front() {
		auto r = result.front;
		T ret;
		foreach(i, a; r) {
			ret[fields[i]] = a;
		}

		return ret;
	}

	@disable this(this) { }

	string[] fields;
	MySql.Result* result;
}
*/


/+
	mysql.linq.tablename.field[key] // select field from tablename where id = key

	mysql.link["name"].table.field[key] // select field from table where name = key


	auto q = mysql.prepQuery("select id from table where something");
	q.sort("name");
	q.limit(start, count);
	q.page(3, pagelength = ?);

	q.execute(params here); // returns the same Result range as query
+/

/*
void main() {
	auto db = new MySql("localhost", "uname", "password", "test");
	foreach(item; db.queryDataObject("SELECT users.*, username
		FROM users, password_manager_accounts
		WHERE password_manager_accounts.user_id =  users.id LIMIT 5")) {
		writefln("item: %s, %s", item.id, item.username);
		item.first = "new";
		item.last = "new2";
		item.username = "kill";
		//item.commitChanges();
	}
}
*/


/*
Copyright: Adam D. Ruppe, 2009 - 2011
License:   <a href="http://www.boost.org/LICENSE_1_0.txt">Boost License 1.0</a>.
Authors: Adam D. Ruppe, with contributions from Nick Sabalausky

        Copyright Adam D. Ruppe 2009 - 2011.
Distributed under the Boost Software License, Version 1.0.
   (See accompanying file LICENSE_1_0.txt or copy at
        http://www.boost.org/LICENSE_1_0.txt)
*/