#include "CrudModel.h"
#include "ASyncWindow.h"
#include "OpenDatabase.h"
#include "PgDatabaseCatalog.h"
#include "PgAttribute.h"
#include "PgAttributeContainer.h"
#include "PgConstraintContainer.h"
#include "GlobalIoService.h"
#include "SqlFormattingUtils.h"
#include "WorkManager.h"
#include "Pgsql_oids.h"
#include <QtConcurrent>
#include <QFuture>
#include <QFutureWatcher>
#include "Pgsql_oids.h"
#include "Pgsql_Params.h"
#include <string>
#include "ScopeGuard.h"

CrudModel::CrudModel(ASyncWindow *async_window)
	: m_asyncWindow(async_window)
	, m_dbConn(*getGlobalAsioIoService())
{
	qDebug("CrudModel created");
	connect(&m_dbConn, &ASyncDBConnection::onStateChanged, this, &CrudModel::connectionStateChanged);
}

CrudModel::~CrudModel()
{
	m_dbConn.closeConnection();
}

/*
 * Strategy
 * when ordered by primary key, offset and limit work very quickly so we can get away with not loading
 * everything.
 */
void CrudModel::setConfig(std::shared_ptr<OpenDatabase> db, const PgClass &table)
{
	m_database = db;
	m_table = table;
	m_primaryKey = db->catalog()->constraints()->getPrimaryForRelation(table.oid());
	//cat->attributes()->getColumnsForRelation()
	callLoadData = true;
	auto dbconfig = m_database->config();
	m_dbConn.setupConnection(dbconfig);
}

QVariant CrudModel::headerData(int section, Qt::Orientation orientation, int role) const
{
	QVariant r;
	if (role == Qt::DisplayRole) {
		if (orientation == Qt::Horizontal) {
			QString s(m_roData->getColName(section));
			s += "\n";
			s += getTypeDisplayString(*m_database->catalog(), getType(section));
			r = s;
		}
		else {
			r = QString::number(section + 1);
		}
	}
	return r;
}


// Basic functionality:
int CrudModel::rowCount(const QModelIndex &/*parent*/) const
{
//	int row_count = m_roData ? m_roData->rows() : 0;

//	todo there will be rownumbers that are not in m_roData

//	++row_count; // one empty new row at the end
	return m_rowCount;
}

int CrudModel::columnCount(const QModelIndex &/*parent*/) const
{
	int col_count = m_roData ? m_roData->cols() : 0;
	return col_count;
}

Oid CrudModel::getType(int column) const
{
	return m_roData ? m_roData->type(column) : InvalidOid;
}

CrudModel::Value CrudModel::getData(const QModelIndex &index) const
{
	Value value;
	if (m_roData) {
		int grid_row = index.row();
		int col = index.column();

		auto row_mapping = m_rowMapping[grid_row];

		const int last_row = rowCount() - 1;

		//Oid o = m_roData->type(col);
		// First see if we have buffered editted values that still need saving
		std::optional<Value> val;
		if (row_mapping.pending) {
			val = m_pendingRowList.getValue(col, row_mapping.rowKey);
		}
		if (row_mapping.modified && !val && grid_row < last_row) { // last_row should never be in modified list, when it is put in modified list a new last row should be created
			// No pending save have a look if we have modified saved data in the modified list
			auto find_res = m_modifiedRowList.find(row_mapping.rowKey);
			if (find_res != m_modifiedRowList.end()) {
				val = find_res->second.data()[col];
			}
		}

		//Value value;
		// If we did not have pending or modified data
		if (!val && row_mapping.rowKey < m_roData->rows()) {
			// Then we are going to read the original data.
			if (!m_roData->null(col, row_mapping.rowKey)) {
				value = std::string(m_roData->val(col, row_mapping.rowKey));
			}
		}
		else {
			if (val) {
				value = *val;
			}
		}
	}
	return value;
}

QVariant CrudModel::data(const QModelIndex &index, int role) const
{
	QVariant v;
	if (role == Qt::EditRole) {
		auto value = getData(index);
		if (value) {
			QString s = QString::fromUtf8(value->c_str());
			v = s;
		}

	}
	else if (role == Qt::DisplayRole) {
		auto value = getData(index);
		if (value) {
			Oid o = m_roData->type(index.column());
			if (o == Pgsql::bool_oid) {
				v = *value == "t"; //s = (s == "t") ? "TRUE" : "FALSE";
			}
			else {
				QString s = QString::fromUtf8(value->c_str());
				if (s.length() > 256) {
					s.truncate(256);
				}
				v = s;
			}
		}
	}
	else if (role == Qt::UserRole) {
		v = getType(index.column());
	}
	return v;
}


void CrudModel::loadData()
{
	QString table_name = m_table->fullyQualifiedQuotedObjectName(); // genFQTableName(*m_database->catalog(), *m_table);
	std::string q = "SELECT * FROM ";
	q += std::string(table_name.toUtf8().data());
	m_dbConn.send(q, [this] (Expected<std::shared_ptr<Pgsql::Result>> res, qint64) {
		if (res.valid()) {
			auto dbres = res.get();
			if (dbres && *dbres) {
				 m_asyncWindow->QueueTask([this, dbres]() { loadIntoModel(dbres); });
			}
		}
		else {
//			emit onQueryError();
		}
	});
}

void CrudModel::loadIntoModel(std::shared_ptr<Pgsql::Result> data)
{
	beginResetModel();
	m_pendingRowList.clear();
	m_modifiedRowList.clear();
	m_roData = data;
	lastRowKey = data->rows();
	m_rowCount = data->rows();
	initRowMapping();
	appendNewRow();
	endResetModel();
}

void CrudModel::initRowMapping()
{
	m_rowMapping.resize(m_rowCount);
	for (int i = 0; i < m_rowCount; ++i)
		m_rowMapping[i]	= { i };
}

void CrudModel::connectionStateChanged(ASyncDBConnection::State state)
{
	switch (state) {
	case ASyncDBConnection::State::NotConnected:
		break;
	case ASyncDBConnection::State::Connecting:
		break;
	case ASyncDBConnection::State::Connected:
		if (callLoadData) {
			callLoadData = false;
			loadData();
		}
		break;
	case ASyncDBConnection::State::QuerySend:

		break;
	case ASyncDBConnection::State::CancelSend:
		break;
	case ASyncDBConnection::State::Terminating:
		break;
	}
}

Qt::ItemFlags CrudModel::flags(const QModelIndex &) const
{
	Qt::ItemFlags flags = Qt::ItemIsSelectable + Qt::ItemIsEnabled;
	if (m_primaryKey) {
		flags |= Qt::ItemIsEditable;
	}
	return flags;
}

bool CrudModel::setData(const QModelIndex &index, const QVariant &value, int role)
{
	if (role == Qt::EditRole) {
		int grid_row = index.row();
		int col = index.column();

		auto& row_mapping = m_rowMapping[grid_row];
		row_mapping.pending = true;

		Value val;
		std::string s = value.toString().toUtf8().data();
		if (!s.empty()) {
			if (s == "''")
				s.clear();
			val = s;
		}
		m_pendingRowList.setValue(col, row_mapping.rowKey, val);

		emit dataChanged(index, index, QVector<int>() << role);
		return true;
	}
	return false;
}

const CrudModel::ModifiedRow* CrudModel::getModifiedRow(int row) const
{
	auto iter = m_modifiedRowList.find(row);
	if (iter == m_modifiedRowList.end())
		return nullptr;
	else
		return &iter->second;
}

CrudModel::PKeyValues CrudModel::getPKeyForRow(int row) const
{
	PKeyValues values;
	values.reserve(m_primaryKey->key.size());

	auto mod_row = getModifiedRow(row);
	if (mod_row){
		for (auto attnum : m_primaryKey->key) {
			const int col = attNumToCol(attnum);
			values.push_back(*(mod_row->data()[col]));
		}
	}
	else if (row < m_roData->rows()){
		for (auto attnum : m_primaryKey->key) {
			int col = attNumToCol(attnum);
			values.push_back(m_roData->get(col, row).c_str());
		}
	}

	return values;
}

Pgsql::Params CrudModel::getPKeyParamsForRow(int row) const
{
	Pgsql::Params params;
	auto mod_row = getModifiedRow(row);
	for (auto attnum : m_primaryKey->key) {
		const int col = attNumToCol(attnum);
		Oid t = getType(col);
		std::string s;
		if (mod_row){
			s = *(mod_row->data()[col]);
		}
		else if (row < m_roData->rows()){
			s = m_roData->get(col, row).c_str();
		}
		params.add(s, t);
	}
	return params;
}


QString CrudModel::columnName(int col) const
{
	return m_roData->getColName(col);
}

std::tuple<QString, Pgsql::Params> CrudModel::createUpdateQuery(const PKeyValues &pkey_values, const PendingRow &pending_row)
{
	Pgsql::Params params;
	auto data = pending_row.data();
	QString table_name = m_table->fullyQualifiedQuotedObjectName(); //genFQTableName(*m_database->catalog(), *m_table);
	QString buffer;
	QTextStream q(&buffer);
	q << "UPDATE " << table_name << " AS d\n  SET ";
	int param = 0;
	for (auto e : data) {
		if (param > 0)
			q << ",";
		q << quoteIdent(columnName(e.first)) << "=$" << ++param;

		// Add value to paramlist
		params.add(e.second, getType(e.first));
	}

	q << "\nWHERE ";
	int i = 0;
	for (auto attnum : m_primaryKey->key) {
		int col = attNumToCol(attnum);
		if (i > 0)
			q << " AND ";
		q << quoteIdent(columnName(col)) << "=$" << ++param;

		params.add(pkey_values[i].c_str(), getType(col));
		++i;
	}
	q << "\nRETURNING *";
	q.flush();
	return { buffer, params };
}

std::tuple<QString, Pgsql::Params> CrudModel::createInsertQuery(const PendingRow &pending_row)
{
	Pgsql::Params params;
	auto data = pending_row.data();
	QString table_name = m_table->fullyQualifiedQuotedObjectName(); // genFQTableName(*m_database->catalog(), *m_table);
	QString buffer;
	QTextStream q(&buffer);
	q << "INSERT INTO " << table_name << "(";

	auto columns = m_database->catalog()->attributes()->getColumnsForRelation(m_table->oid());
	bool first = true;
	for (auto e : data) {
		int num = e.first + 1;
		auto find_res = std::find_if(columns.begin(), columns.end(),
					 [num] (const auto &elem) -> bool { return num == elem.num; });
		if (find_res != columns.end()) {
			if (first) first = false;
			else q << ",";
			q << find_res->name;
		}
	}
	q << ") VALUES ($1";
	for (size_t p = 2; p <= data.size(); ++p)
		q << ",$" << p;
	q << ") RETURNING *";
	for (auto e : data) {
		// Add value to paramlist

		params.add(e.second, getType(e.first));
	}
	q.flush();
	return { buffer, params };
}

std::tuple<QString, Pgsql::Params> CrudModel::createDeleteStatement(const PKeyValues &pkey_values)
{
	Pgsql::Params params;
	size_t i = 0;
	for (auto attnum : m_primaryKey->key) {
		const int col = attNumToCol(attnum);
		params.add(pkey_values[i].c_str(), getType(col));
		++i;
	}

	return { createDeleteStatement(), params };
}

QString CrudModel::createDeleteStatement() const
{
	Pgsql::Params params;
	QString table_name = m_table->fullyQualifiedQuotedObjectName();
	QString buffer;
	QTextStream q(&buffer);
	q << "DELETE FROM " << table_name;
	q << "\nWHERE ";
	int i = 0;
	for (auto attnum : m_primaryKey->key) {
		const int col = attNumToCol(attnum);
		if (i > 0)
			q << " AND ";
		q << quoteIdent(columnName(col)) << "=$" << ++i;
	}

	q.flush();
	return buffer;
}


std::tuple<bool, CrudModel::ModifiedRow> CrudModel::updateRow(const PendingRow &pending_row)
{
	auto data = pending_row.data();

	if (!data.empty()) {
		auto pkey_values = getPKeyForRow(pending_row.row());

		QString buffer;
		Pgsql::Params params;
		if (pkey_values.empty()){
			std::tie(buffer, params) = createInsertQuery(pending_row);
		}
		else {
			std::tie(buffer, params) = createUpdateQuery(pkey_values, pending_row);
		}


		int row_number = pending_row.row();
		Pgsql::Connection db_update_conn;
		auto dbconfig = m_database->config();
		bool res = db_update_conn.connect(dbconfig.getKeywords(), dbconfig.getValues(), false);
		if (res) {
			auto result = db_update_conn.queryParam(buffer, params);
			if (result && result.rows() == 1) {

				std::vector<Value> values;
				auto row = *result.begin();
				for (auto v : row) {
					if (v.null())
						values.push_back(Value());
					else
						values.push_back(std::string(v.c_str()));
				}

				ModifiedRow modified_row(row_number, values);

				return { true, modified_row };
			}
		}

	}
	return { false, {} };
}

bool CrudModel::savePendingChanges()
{
	while (!m_pendingRowList.m_rows.empty()) {
		auto iter = m_pendingRowList.m_rows.begin();
		auto [ok, modified_row] = updateRow(iter->second);
		if (ok) {
			int rowKey = iter->first;
			m_modifiedRowList.insert_or_assign(rowKey, modified_row);
			m_pendingRowList.m_rows.erase(iter);

			auto iter = std::find_if(m_rowMapping.begin(), m_rowMapping.end(),
								  [rowKey](const RowMapping &rhs) -> auto { return rhs.rowKey == rowKey; });
			if (iter != m_rowMapping.end()) {
				iter->modified = true;
				iter->pending = false;
				int row = iter - m_rowMapping.begin();
				if (row == m_rowCount - 1)
					appendNewRow();

			}


		}
		else {
			return false;
		}
	}

	return true;
}

bool CrudModel::submit()
{
	return savePendingChanges();
}

void CrudModel::revert()
{

}

void CrudModel::appendNewRow()
{
	int row = m_rowCount;
	beginInsertRows(QModelIndex(), row, row);
	m_rowMapping.emplace_back(allocNewRowKey());
	++m_rowCount;
	endInsertRows();
}

void CrudModel::removeRows()
{
//	determine selection
//			remove selected rows

}

bool CrudModel::removeRows(int row, int count, const QModelIndex &parent)
{
	if (m_rowMapping.empty()) return false;
	// When removing rows there is no direct mapping anymore between the rows in the grid
	// and the rows in m_roData

	// Therefor we need an indirection to keep track of which rows are visible and which
	// grid row maps to what data row. Maybe we can also keep track where the current data
	// of the row is located original data, pending data or modified data

	// 1. Get PKEY and remove that row from table

	Pgsql::Connection db_update_conn;
	auto dbconfig = m_database->config();
	bool res = db_update_conn.connect(dbconfig.getKeywords(), dbconfig.getValues(), false);
	if (!res) {
		return false;
	}

	// First delete rows in table
	QString delete_statement = createDeleteStatement();
	db_update_conn.query("BEGIN;");
	for (int current_row = row; current_row < row + count; ++current_row) {
		auto&& mapping = m_rowMapping[static_cast<size_t>(current_row)];
		auto params = getPKeyParamsForRow(mapping.rowKey);
		if (!params.empty()) {
			// Execute DELETE
			auto result = db_update_conn.queryParam(delete_statement, params);
		}
	}
	db_update_conn.query("COMMIT;");
	// Then from model
	{
		beginRemoveRows(parent, row, row);
		SCOPE_EXIT { endRemoveRows(); };
		for (int current_row = row; current_row < row + count; ++current_row) {
			auto&& mapping = m_rowMapping[static_cast<size_t>(current_row)];

			// if the row is in modified it can be removed from modified
			if (mapping.modified) {
				m_modifiedRowList.erase(mapping.rowKey);
			}
			/// \todo can it be pending? should be removed if it is.

		}
		// remove the rows from m_rowMapping
		auto first = m_rowMapping.begin() + row;
		m_rowMapping.erase(first, first + count);
	}
	return true;
}