/++
	SQLite implementation of the [arsd.database.Database] interface.


	Compile with `-version=sqlite_extended_metadata_available` if your sqlite is compiled with the `SQLITE_ENABLE_COLUMN_METADATA` C-preprocessor symbol.

	If you enable that, you get the ability to use the queryDataObject() function with sqlite. (You can still use DataObjects, but you'll have to set up the mappings manually without the extended metadata.)

	History:
		Originally written prior to July 2011 (before arsd on git).

		Only lightly modified before then and May 2024 when it got an overhaul.

		FIXME: `PRAGMA foreign_keys = ON` is something i wanna enable by default in here.
+/
module arsd.sqlite;

version(static_sqlite) {} else
	pragma(lib, "sqlite3");
version(linux)
	pragma(lib, "dl"); // apparently sqlite3 depends on this

public import arsd.database;

import core.stdc.stdlib;
import core.exception;
import core.memory;
import std.conv;
import std.string;
import std.exception;

/*
	NOTE:

	This only works correctly on INSERTs if the user can grow the
	database file! This means he must have permission to write to
	both the file and the directory it is in.

*/


/++
	The Database interface provides a consistent and safe way to access sql RDBMSs.

	Why are all the classes scope? To ensure the database connection is closed when you are done with it.
	The destructor cleans everything up.

	(maybe including rolling back a transaction if one is going and it errors.... maybe, or that could bne
	scope(exit))
+/
Sqlite openDBAndCreateIfNotPresent(string filename, string sql, scope void delegate(Sqlite db) initialize = null){
	static import std.file;
	if(std.file.exists(filename))
		return new Sqlite(filename);
	else {
		auto db = new Sqlite(filename);
		db.exec(sql);
		if(initialize !is null)
			initialize(db);
		return db;
	}
}

/*
import std.stdio;
void main() {
	Database db = new Sqlite("test.sqlite.db");

	db.query("CREATE TABLE users (id integer, name text)");

	db.query("INSERT INTO users values (?, ?)", 1, "hello");

	foreach(line; db.query("SELECT * FROM users")) {
		writefln("%s %s", line[0], line["name"]);
	}
}
*/

/++

+/
class Sqlite : Database {
  public:
	/++
		Opens and creates the database, if desired.

		History:
			The `flags` argument was ignored until July 29, 2022. (This function was originally written over 11 years ago, when sqlite3_open_v2 was not commonly supported on some distributions yet, and I didn't notice to revisit it for ages!)
	+/
	this(string filename, int flags = SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE) {
		int error = sqlite3_open_v2(toStringz(filename), &db, flags, null);
		if(error != SQLITE_OK)
			throw new DatabaseConnectionException(this.error());
	/+
		int error = sqlite3_open(toStringz(filename), &db);
		if(error != SQLITE_OK)
			throw new DatabaseException(this.error());
	+/
	}

	~this(){
		if(sqlite3_close(db) != SQLITE_OK)
			throw new DatabaseException(error());
	}

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

	// my extension for easier editing
	version(sqlite_extended_metadata_available) {
		ResultByDataObject queryDataObject(T...)(string sql, T t) {
			// modify sql for the best data object grabbing
			sql = fixupSqlForDataObjectUse(sql);

			auto s = Statement(this, sql);
			foreach(i, arg; t) {
				s.bind(i + 1, arg);
			}

			auto magic = s.execute(true); // fetch extended metadata

			return ResultByDataObject(cast(SqliteResult) magic, magic.extendedMetadata, this);
		}
	}

	override bool isAlive() {
		return true;
	}

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

	override ResultSet queryImpl(string sql, Variant[] args...) {
		auto s = Statement(this, sql);
		foreach(i, arg; args) {
			s.bind(cast(int) i + 1, arg);
		}
		return s.execute();
	}

	override string escape(string sql) @system {
		if(sql is null)
			return null;
		char* got = sqlite3_mprintf("%q", toStringz(sql)); // FIXME: might have to be %Q, need to check this, but I think the other impls do the same as %q
		auto orig = got;
		string esc;
		while(*got) {
			esc ~= (*got);
			got++;
		}

		sqlite3_free(orig);

		return esc;
	}

	string escapeBinaryString(const(ubyte)[] b) {
		return tohexsql(b);
	}

	string error() @system {
		import core.stdc.string : strlen;
		char* mesg = sqlite3_errmsg(db);
		char[] m;
		sizediff_t a = strlen(mesg);
		m.length = a;
		for(int v = 0; v < a; v++)
			m[v] = mesg[v];

		return assumeUnique(m);
	}

	///
	int affectedRows(){
		return sqlite3_changes(db);
	}

	///
	int lastInsertId(){
		return cast(int) sqlite3_last_insert_rowid(db);
	}


	int exec(string sql, void delegate (char[][char[]]) onEach = null) @system {
		char* mesg;
		if(sqlite3_exec(db, toStringz(sql), &callback, &onEach, &mesg) != SQLITE_OK) {
			import core.stdc.string : strlen;
			char[] m;
			sizediff_t a = strlen(mesg);
			m.length = a;
			for(int v = 0; v < a; v++)
				m[v] = mesg[v];

			sqlite3_free(mesg);
			throw new SqlException("exec " ~ m.idup);
		}

		return 0;
	}
/*
	Statement prepare(string sql){
		sqlite3_stmt * s;
		if(sqlite3_prepare_v2(db, toStringz(sql), cast(int) sql.length, &s, null) != SQLITE_OK)
			throw new DatabaseException("prepare " ~ error());

		Statement a = new Statement(s);

		return a;
	}
*/
  private:
	sqlite3* db;
}


class SqliteResult :  ResultSet {
	int getFieldIndex(string field) {
		foreach(i, n; columnNames)
			if(n == field)
				return cast(int) i;
		throw new Exception("no such field " ~ field);
	}

	string[] fieldNames() {
		return columnNames;
	}

	// this is a range that can offer other ranges to access it
	bool empty() {
		return position == rows.length;
	}

	Row front() {
		Row r;

		r.resultSet = this;
		if(rows.length <= position)
			throw new Exception("Result is empty");
		foreach(c; rows[position]) {
			if(auto t = c.peek!(immutable(ubyte)[]))
				r.row ~= DatabaseDatum(cast(string) *t);
			else if (auto d = c.peek!double)
				// 17 significant decimal digits are enough to not lose precision (IEEE 754 section 5.12.2)
				r.row ~= DatabaseDatum(format!"%.17s"(*d));
			else {
				r.row ~= DatabaseDatum(c.coerce!(string));
			}
		}

		return r;
	}

	void popFront() {
		position++;
	}

	override size_t length() {
		return rows.length;
	}

	this(Variant[][] rows, char[][] columnNames) {
		this.rows = rows;
		foreach(c; columnNames)
			this.columnNames ~= c.idup;
	}

    private:
	string[] columnNames;
	Variant[][] rows;
	int position = 0;
}


struct Statement {
	private this(Sqlite db, sqlite3_stmt * S) {
		this.db = db;
		s = S;
		finalized = false;
	}

	Sqlite db;

	this(Sqlite db, string sql) {
		// the arsd convention is zero based ?, but sqlite insists on one based. so this is stupid but still
		if(sql.indexOf("?0") != -1) {
			foreach_reverse(i; 0 .. 10)
				sql = sql.replace("?" ~ to!string(i), "?" ~ to!string(i + 1));
		}

		this.db = db;
		if(sqlite3_prepare_v2(db.db, toStringz(sql), cast(int) sql.length, &s, null) != SQLITE_OK)
			throw new SqlException(db.error() ~ " " ~ sql);
	}

	version(sqlite_extended_metadata_available)
		Tuple!(string, string)[string] extendedMetadata;

	ResultSet execute(bool fetchExtendedMetadata = false) @system {
		bool first = true;
		int count;
		int numRows = 0;
		int r = 0;
		// FIXME: doesn't handle busy database
		while( SQLITE_ROW == sqlite3_step(s) ){
			numRows++;
			if(numRows >= rows.length)
				rows.length = rows.length + 8;

			if(first){
				count = sqlite3_column_count(s);

				columnNames.length = count;
				for(int a = 0; a < count; a++){
					import core.stdc.string : strlen;
					char* str = sqlite3_column_name(s, a);
					sizediff_t l = strlen(str);
					columnNames[a].length = l;
					for(int b = 0; b < l; b++)
						columnNames[a][b] = str[b];

					version(sqlite_extended_metadata_available) {
					if(fetchExtendedMetadata) {
						string origtbl;
						string origcol;

						const(char)* rofl;

						rofl = sqlite3_column_table_name(s, a);
						if(rofl is null)
							throw new Exception("null table name pointer");
						while(*rofl) {
							origtbl ~= *rofl;
							rofl++;
						}
						rofl = sqlite3_column_origin_name(s, a);
						if(rofl is null)
							throw new Exception("null colum name pointer");
						while(*rofl) {
							origcol ~= *rofl;
							rofl++;
						}
						extendedMetadata[columnNames[a].idup] = tuple(origtbl, origcol);
					}
					}
				}

				first = false;
			}


			rows[r].length = count;

			for(int a = 0; a < count; a++){
				Variant v;
				final switch(sqlite3_column_type(s, a)){
					case SQLITE_INTEGER:
						v = sqlite3_column_int64(s, a);
					break;
					case SQLITE_FLOAT:
						v = sqlite3_column_double(s, a);
					break;
					case SQLITE3_TEXT:
						char* str = sqlite3_column_text(s, a);
						char[] st;

						import core.stdc.string : strlen;
						sizediff_t l = strlen(str);
						st.length = l;
						st[] = str[0 ..l];

						v = assumeUnique(st);
					break;
					case SQLITE_BLOB:
						ubyte* str = cast(ubyte*) sqlite3_column_blob(s, a);
						ubyte[] st;

						int l = sqlite3_column_bytes(s, a);
						st.length = l;
						st[] = str[0 .. l];

						v = assumeUnique(st);
					break;
					case SQLITE_NULL:
						string n = null;
						v = n;
					break;
				}

				rows[r][a] = v;
			}

			r++;
		}

		rows.length = numRows;
		length = numRows;
		position = 0;
		executed = true;
		reset();

		return new SqliteResult(rows.dup, columnNames);
	}

/*
template extract(A, T, R...){
	void extract(A args, out T t, out R r){
		if(r.length + 1 != args.length)
			throw new DatabaseException("wrong places");
		args[0].to(t);
		static if(r.length)
			extract(args[1..$], r);
	}
}
*/
/*
	bool next(T, R...)(out T t, out R r){
		if(position == length)
			return false;

		extract(rows[position], t, r);

		position++;
		return true;
	}
*/
	bool step(out Variant[] row){
		assert(executed);
		if(position == length)
			return false;

		row = rows[position];
		position++;

		return true;
	}

	bool step(out Variant[char[]] row){
		assert(executed);
		if(position == length)
			return false;

		for(int a = 0; a < length; a++)
			row[columnNames[a].idup] = rows[position][a];

		position++;

		return true;
	}

	void reset(){
		if(sqlite3_reset(s) != SQLITE_OK)
			throw new DatabaseException("reset " ~ db.error());
	}

	void resetBindings(){
		sqlite3_clear_bindings(s);
	}

	void resetAll(){
		reset;
		resetBindings;
		executed = false;
	}

	int bindNameLookUp(const char[] name){
		int a = sqlite3_bind_parameter_index(s, toStringz(name));
		if(a == 0)
			throw new DatabaseException("bind name lookup failed " ~ db.error());
		return a;
	}

	bool next(T, R...)(out T t, out R r){
		assert(executed);
		if(position == length)
			return false;

		extract(rows[position], t, r);

		position++;
		return true;
	}

	template bindAll(T, R...){
		void bindAll(T what, R more){
			bindAllHelper(1, what, more);
		}
	}

	template exec(T, R...){
		void exec(T what, R more){
			bindAllHelper(1, what, more);
			execute();
		}
	}

	void bindAllHelper(A, T, R...)(A where, T what, R more){
		bind(where, what);
		static if(more.length)
			bindAllHelper(where + 1, more);
	}

	//void bind(T)(string name, T value) {
		//bind(bindNameLookUp(name), value);
	//}

		// This should be a template, but grrrr.
		void bind (const char[] name, const char[] value){ bind(bindNameLookUp(name), value); }
		void bind (const char[] name, int value){ bind(bindNameLookUp(name), value); }
		void bind (const char[] name, float value){ bind(bindNameLookUp(name), value); }
		void bind (const char[] name, double value){ bind(bindNameLookUp(name), value); }
		void bind (const char[] name, const byte[] value){ bind(bindNameLookUp(name), value); }
		void bind (const char[] name, const ubyte[] value){ bind(bindNameLookUp(name), value); }

	void bind(int col, typeof(null) value){
		if(sqlite3_bind_null(s, col) != SQLITE_OK)
			throw new DatabaseException("bind " ~ db.error());
	}
	void bind(int col, const char[] value){
		if(sqlite3_bind_text(s, col, value.ptr is null ? "" : value.ptr, cast(int) value.length, cast(void*)-1) != SQLITE_OK)
			throw new DatabaseException("bind " ~ db.error());
	}

	void bind(int col, float value){
		if(sqlite3_bind_double(s, col, value) != SQLITE_OK)
			throw new DatabaseException("bind " ~ db.error());
	}

	void bind(int col, double value){
		if(sqlite3_bind_double(s, col, value) != SQLITE_OK)
			throw new DatabaseException("bind " ~ db.error());
	}

	void bind(int col, int value){
		if(sqlite3_bind_int(s, col, value) != SQLITE_OK)
			throw new DatabaseException("bind " ~ db.error());
	}

	void bind(int col, long value){
		if(sqlite3_bind_int64(s, col, value) != SQLITE_OK)
			throw new DatabaseException("bind " ~ db.error());
	}

	void bind(int col, const ubyte[] value){
		if(value is null) {
			if(sqlite3_bind_null(s, col) != SQLITE_OK)
				throw new DatabaseException("bind " ~ db.error());
		} else {
			if(sqlite3_bind_blob(s, col, cast(void*)value.ptr, cast(int) value.length, cast(void*)-1) != SQLITE_OK)
				throw new DatabaseException("bind " ~ db.error());
		}
	}

	void bind(int col, const byte[] value){
		if(value is null) {
			if(sqlite3_bind_null(s, col) != SQLITE_OK)
				throw new DatabaseException("bind " ~ db.error());
		} else {
			if(sqlite3_bind_blob(s, col, cast(void*)value.ptr, cast(int) value.length, cast(void*)-1) != SQLITE_OK)
				throw new DatabaseException("bind " ~ db.error());
		}
	}

	void bind(int col, Variant v) {
		if(v.peek!long)
			bind(col, v.get!long);
		else if(v.peek!ulong)
			bind(col, v.get!ulong);
		else if(v.peek!int)
			bind(col, v.get!int);
		else if(v.peek!(const(int)))
			bind(col, v.get!(const(int)));
		else if(v.peek!bool)
			bind(col, v.get!bool ? 1 : 0);
		else if(v.peek!DateTime)
			bind(col, v.get!DateTime.toISOExtString());
		else if(v.peek!string)
			bind(col, v.get!string);
		else if(v.peek!float)
			bind(col, v.get!float);
		else if(v.peek!double)
			bind(col, v.get!double);
		else if(v.peek!(byte[]))
			bind(col, v.get!(byte[]));
		else if(v.peek!(ubyte[]))
			bind(col, v.get!(ubyte[]));
		else if(v.peek!(immutable(ubyte)[]))
			bind(col, v.get!(immutable(ubyte)[]));
		else if(v.peek!(void*) && v.get!(void*) is null)
			bind(col, null);
		else
			bind(col, v.coerce!string);
		//assert(0, v.type.toString ~ " " ~ v.coerce!string);
	}

	~this(){
		if(!finalized)
			finalize();
	}

	void finalize(){
		if(finalized)
			return;
		if(sqlite3_finalize(s) != SQLITE_OK)
			throw new DatabaseException("finalize " ~ db.error());
		finalized = true;
	}
  private:
	Variant[][] rows;
	char[][]  columnNames;
	int length;
	int position;
	bool finalized;

	sqlite3_stmt * s;

	bool executed;

}


version(sqlite_extended_metadata_available) {
	import std.typecons;
	struct ResultByDataObject {
		this(SqliteResult r, Tuple!(string, string)[string] mappings, Sqlite db) {
			result = r;
			this.db = db;
			this.mappings = mappings;
		}

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

		ulong length() { return result.length; }
		bool empty() { return result.empty; }
		void popFront() { result.popFront(); }
		DataObject front() {
			return new DataObject(db, 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) { }

		SqliteResult result;
		Sqlite db;
	}
}


extern(C) int callback(void* cb, int howmany, char** text, char** columns) @system {
	if(cb is null)
		return 0;

	void delegate(char[][char[]]) onEach = *cast(void delegate(char[][char[]])*) cb;

	char[][char[]] row;
	import core.stdc.string : strlen;

	for(int a = 0; a < howmany; a++){
		sizediff_t b = strlen(columns[a]);
		char[] buf;
		buf.length = b;
		for(int c = 0; c < b; c++)
			buf[c] = columns[a][c];

		sizediff_t d = strlen(text[a]);
		char[] t;
		t.length = d;
		for(int c = 0; c < d; c++)
			t[c] = text[a][c];

		row[buf.idup] = t;
	}

	onEach(row);

	return 0;
}

extern(C) {
	struct sqlite3;
	struct sqlite3_stmt;

	enum int SQLITE_OK = 0;
	enum int SQLITE_ROW = 100;
	enum int SQLITE_DONE = 101;

	enum int SQLITE_INTEGER = 1; // int
	enum int SQLITE_FLOAT = 2;   // float
	enum int SQLITE3_TEXT = 3;   // char[]
	enum int SQLITE_BLOB = 4;    // ubyte[]
	enum int SQLITE_NULL = 5;    // void* = null

	enum int SQLITE_DELETE = 9; // table name, null
	enum int SQLITE_INSERT = 18; // table name, null
	enum int SQLITE_UPDATE = 23; // table name, column name

	enum int SQLITE_OPEN_READONLY = 0x1;
	enum int SQLITE_OPEN_READWRITE = 0x2;
	enum int SQLITE_OPEN_CREATE = 0x4;
	enum int SQLITE_CANTOPEN = 14;


	int sqlite3_changes(sqlite3*);
	int sqlite3_close(sqlite3 *);
	int sqlite3_exec(
		sqlite3*,                                  /* An open database */
		const(char) *sql,                           /* SQL to be evaluted */
		int function(void*,int,char**,char**),  /* Callback function */
		void *,                                    /* 1st argument to callback */
		char **errmsg                              /* Error msg written here */
	);

	int sqlite3_open(
		const(char) *filename,   /* Database filename (UTF-8) */
		sqlite3 **ppDb          /* OUT: SQLite db handle */
	);

	int sqlite3_open_v2(
		const char *filename,   /* Database filename (UTF-8) */
		sqlite3 **ppDb,         /* OUT: SQLite db handle */
		int flags,              /* Flags */
		const char *zVfs        /* Name of VFS module to use */
	);

	int sqlite3_prepare_v2(
		sqlite3 *db,            /* Database handle */
		const(char) *zSql,       /* SQL statement, UTF-8 encoded */
		int nByte,              /* Maximum length of zSql in bytes. */
		sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
		char **pzTail     /* OUT: Pointer to unused portion of zSql */
	);

	int sqlite3_finalize(sqlite3_stmt *pStmt);
	int sqlite3_step(sqlite3_stmt*);
	long sqlite3_last_insert_rowid(sqlite3*);

	char *sqlite3_mprintf(const char*,...);

	int sqlite3_reset(sqlite3_stmt *pStmt);
	int sqlite3_clear_bindings(sqlite3_stmt*);
	int sqlite3_bind_parameter_index(sqlite3_stmt*, const(char) *zName);

	int sqlite3_bind_blob(sqlite3_stmt*, int, void*, int n, void*);
	//int sqlite3_bind_blob(sqlite3_stmt*, int, void*, int n, void(*)(void*));
	int sqlite3_bind_double(sqlite3_stmt*, int, double);
	int sqlite3_bind_int(sqlite3_stmt*, int, int);
	int sqlite3_bind_int64(sqlite3_stmt*, int, long);
	int sqlite3_bind_null(sqlite3_stmt*, int);
	int sqlite3_bind_text(sqlite3_stmt*, int, const(char)*, int n, void*);
	//int sqlite3_bind_text(sqlite3_stmt*, int, char*, int n, void(*)(void*));

	void *sqlite3_column_blob(sqlite3_stmt*, int iCol);
	int sqlite3_column_bytes(sqlite3_stmt*, int iCol);
	double sqlite3_column_double(sqlite3_stmt*, int iCol);
	int sqlite3_column_int(sqlite3_stmt*, int iCol);
	long sqlite3_column_int64(sqlite3_stmt*, int iCol);
	char *sqlite3_column_text(sqlite3_stmt*, int iCol);
	int sqlite3_column_type(sqlite3_stmt*, int iCol);
	char *sqlite3_column_name(sqlite3_stmt*, int N);

	int sqlite3_column_count(sqlite3_stmt *pStmt);
	void sqlite3_free(void*);
	char *sqlite3_errmsg(sqlite3*);

	// will need these to enable support for DataObjects here
	const(char*) sqlite3_column_database_name(sqlite3_stmt*,int);
	const(char*) sqlite3_column_table_name(sqlite3_stmt*,int);
	const(char*) sqlite3_column_origin_name(sqlite3_stmt*,int);

	// https://www.sqlite.org/c3ref/update_hook.html
	void* sqlite3_update_hook(sqlite3* db, updatehookcallback cb, void* userData); // returns the old userData
}

extern(C) alias updatehookcallback = void function(void* userData, int op, char* databaseName, char* tableName, /* sqlite3_int64 */ long rowid);