# -*- coding: utf-8 -*-

"""
/***************************************************************************
Name                 : DB Manager
Description          : Database manager plugin for QGIS
Date                 : May 23, 2011
copyright            : (C) 2011 by Giuseppe Sucameli
email                : brush.tyler@gmail.com

 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/
"""
from builtins import str
from builtins import range

from qgis.PyQt.QtCore import (Qt,
                              QTime,
                              QRegExp,
                              QAbstractTableModel,
                              pyqtSignal,
                              QObject)
from qgis.PyQt.QtGui import (QFont,
                             QStandardItemModel,
                             QStandardItem)
from qgis.PyQt.QtWidgets import QApplication

from qgis.core import QgsTask

from .plugin import DbError, BaseError


class BaseTableModel(QAbstractTableModel):

    def __init__(self, header=None, data=None, parent=None):
        QAbstractTableModel.__init__(self, parent)
        self._header = header if header else []
        self.resdata = data if data else []

    def headerToString(self, sep="\t"):
        header = self._header
        return sep.join(header)

    def rowToString(self, row, sep="\t"):
        return sep.join(
            str(self.getData(row, col))
            for col in range(self.columnCount())
        )

    def getData(self, row, col):
        return self.resdata[row][col]

    def columnNames(self):
        return list(self._header)

    def rowCount(self, parent=None):
        return len(self.resdata)

    def columnCount(self, parent=None):
        return len(self._header)

    def data(self, index, role):
        if role not in [Qt.DisplayRole,
                        Qt.EditRole,
                        Qt.FontRole]:
            return None

        val = self.getData(index.row(), index.column())

        if role == Qt.EditRole:
            return val

        if role == Qt.FontRole:  # draw NULL in italic
            if val is not None:
                return None
            f = QFont()
            f.setItalic(True)
            return f

        if val is None:
            return "NULL"
        elif isinstance(val, memoryview):
            # hide binary data
            return None
        elif isinstance(val, str) and len(val) > 300:
            # too much data to display, elide the string
            val = val[:300]
        try:
            return str(val)  # convert to Unicode
        except UnicodeDecodeError:
            return str(val, 'utf-8', 'replace')  # convert from utf8 and replace errors (if any)

    def headerData(self, section, orientation, role):
        if role != Qt.DisplayRole:
            return None

        if orientation == Qt.Vertical:
            # header for a row
            return section + 1
        else:
            # header for a column
            return self._header[section]


class TableDataModel(BaseTableModel):

    def __init__(self, table, parent=None):
        self.db = table.database().connector
        self.table = table

        fieldNames = [x.name for x in table.fields()]
        BaseTableModel.__init__(self, fieldNames, None, parent)

        # get table fields
        self.fields = []
        for fld in table.fields():
            self.fields.append(self._sanitizeTableField(fld))

        self.fetchedCount = 201
        self.fetchedFrom = -self.fetchedCount - 1  # so the first call to getData will exec fetchMoreData(0)

    def _sanitizeTableField(self, field):
        """ quote column names to avoid some problems (e.g. columns with upper case) """
        return self.db.quoteId(field)

    def getData(self, row, col):
        if row < self.fetchedFrom or row >= self.fetchedFrom + self.fetchedCount:
            margin = self.fetchedCount / 2
            start = int(self.rowCount() - margin if row + margin >= self.rowCount() else row - margin)
            if start < 0:
                start = 0
            self.fetchMoreData(start)
        return self.resdata[row - self.fetchedFrom][col]

    def fetchMoreData(self, row_start):
        pass

    def rowCount(self, index=None):
        # case for tables with no columns ... any reason to use them? :-)
        return self.table.rowCount if self.table.rowCount is not None and self.columnCount(index) > 0 else 0


class SqlResultModelAsync(QObject):
    done = pyqtSignal()

    def __init__(self):
        super().__init__()
        self.error = BaseError('')
        self.status = None
        self.model = None
        self.task = None
        self.canceled = False

    def cancel(self):
        self.canceled = True
        if self.task:
            self.task.cancel()

    def modelDone(self):
        if self.task:
            self.status = self.task.status
            self.model = self.task.model
            self.error = self.task.error

        self.done.emit()


class SqlResultModelTask(QgsTask):

    def __init__(self, db, sql, parent):
        super().__init__(description=QApplication.translate("DBManagerPlugin", "Executing SQL"))
        self.db = db
        self.sql = sql
        self.parent = parent
        self.error = BaseError('')
        self.model = None


class SqlResultModel(BaseTableModel):

    def __init__(self, db, sql, parent=None):
        self.db = db.connector

        t = QTime()
        t.start()
        c = self.db._execute(None, sql)

        self._affectedRows = 0
        data = []
        header = self.db._get_cursor_columns(c)
        if header is None:
            header = []

        try:
            if len(header) > 0:
                data = self.db._fetchall(c)
            self._affectedRows = len(data)
        except DbError:
            # nothing to fetch!
            data = []
            header = []

        super().__init__(header, data, parent)

        # commit before closing the cursor to make sure that the changes are stored
        self.db._commit()
        c.close()
        self._secs = t.elapsed() / 1000.0
        del c
        del t

    def secs(self):
        return self._secs

    def affectedRows(self):
        return self._affectedRows


class SimpleTableModel(QStandardItemModel):

    def __init__(self, header, editable=False, parent=None):
        self.header = header
        self.editable = editable
        QStandardItemModel.__init__(self, 0, len(self.header), parent)

    def rowFromData(self, data):
        row = []
        for c in data:
            item = QStandardItem(str(c))
            item.setFlags((item.flags() | Qt.ItemIsEditable) if self.editable else (item.flags() & ~Qt.ItemIsEditable))
            row.append(item)
        return row

    def headerData(self, section, orientation, role):
        if orientation == Qt.Horizontal and role == Qt.DisplayRole:
            return self.header[section]
        return None

    def _getNewObject(self):
        pass

    def getObject(self, row):
        return self._getNewObject()

    def getObjectIter(self):
        for row in range(self.rowCount()):
            yield self.getObject(row)


class TableFieldsModel(SimpleTableModel):

    def __init__(self, parent, editable=False):
        SimpleTableModel.__init__(self, ['Name', 'Type', 'Null', 'Default', 'Comment'], editable, parent)

    def headerData(self, section, orientation, role):
        if orientation == Qt.Vertical and role == Qt.DisplayRole:
            return section + 1
        return SimpleTableModel.headerData(self, section, orientation, role)

    def flags(self, index):
        flags = SimpleTableModel.flags(self, index)
        if index.column() == 2 and flags & Qt.ItemIsEditable:  # set Null column as checkable instead of editable
            flags = flags & ~Qt.ItemIsEditable | Qt.ItemIsUserCheckable
        return flags

    def append(self, fld):
        data = [fld.name, fld.type2String(), not fld.notNull, fld.default2String(), fld.getComment()]
        self.appendRow(self.rowFromData(data))
        row = self.rowCount() - 1
        self.setData(self.index(row, 0), fld, Qt.UserRole)
        self.setData(self.index(row, 1), fld.primaryKey, Qt.UserRole)
        self.setData(self.index(row, 2), None, Qt.DisplayRole)
        self.setData(self.index(row, 2), Qt.Unchecked if fld.notNull else Qt.Checked, Qt.CheckStateRole)

    def _getNewObject(self):
        from .plugin import TableField

        return TableField(None)

    def getObject(self, row):
        val = self.data(self.index(row, 0), Qt.UserRole)
        fld = val if val is not None else self._getNewObject()
        fld.name = self.data(self.index(row, 0)) or ""
        typestr = self.data(self.index(row, 1)) or ""
        regex = QRegExp("([^\\(]+)\\(([^\\)]+)\\)")
        startpos = regex.indexIn(typestr)
        if startpos >= 0:
            fld.dataType = regex.cap(1).strip()
            fld.modifier = regex.cap(2).strip()
        else:
            fld.modifier = None
            fld.dataType = typestr

        fld.notNull = self.data(self.index(row, 2), Qt.CheckStateRole) == Qt.Unchecked
        fld.primaryKey = self.data(self.index(row, 1), Qt.UserRole)
        fld.comment = self.data(self.index(row, 4))
        return fld

    def getFields(self):
        return [
            fld
            for fld in self.getObjectIter()
        ]


class TableConstraintsModel(SimpleTableModel):

    def __init__(self, parent, editable=False):
        SimpleTableModel.__init__(self, [QApplication.translate("DBManagerPlugin", 'Name'),
                                         QApplication.translate("DBManagerPlugin", 'Type'),
                                         QApplication.translate("DBManagerPlugin", 'Column(s)')], editable, parent)

    def append(self, constr):
        field_names = [str(k_v[1].name) for k_v in iter(list(constr.fields().items()))]
        data = [constr.name, constr.type2String(), ", ".join(field_names)]
        self.appendRow(self.rowFromData(data))
        row = self.rowCount() - 1
        self.setData(self.index(row, 0), constr, Qt.UserRole)
        self.setData(self.index(row, 1), constr.type, Qt.UserRole)
        self.setData(self.index(row, 2), constr.columns, Qt.UserRole)

    def _getNewObject(self):
        from .plugin import TableConstraint

        return TableConstraint(None)

    def getObject(self, row):
        constr = self.data(self.index(row, 0), Qt.UserRole)
        if not constr:
            constr = self._getNewObject()
        constr.name = self.data(self.index(row, 0)) or ""
        constr.type = self.data(self.index(row, 1), Qt.UserRole)
        constr.columns = self.data(self.index(row, 2), Qt.UserRole)
        return constr

    def getConstraints(self):
        return [
            constr
            for constr in self.getObjectIter()
        ]


class TableIndexesModel(SimpleTableModel):

    def __init__(self, parent, editable=False):
        SimpleTableModel.__init__(self, [QApplication.translate("DBManagerPlugin", 'Name'),
                                         QApplication.translate("DBManagerPlugin", 'Column(s)')], editable, parent)

    def append(self, idx):
        field_names = [str(k_v1[1].name) for k_v1 in iter(list(idx.fields().items()))]
        data = [idx.name, ", ".join(field_names)]
        self.appendRow(self.rowFromData(data))
        row = self.rowCount() - 1
        self.setData(self.index(row, 0), idx, Qt.UserRole)
        self.setData(self.index(row, 1), idx.columns, Qt.UserRole)

    def _getNewObject(self):
        from .plugin import TableIndex

        return TableIndex(None)

    def getObject(self, row):
        idx = self.data(self.index(row, 0), Qt.UserRole)
        if not idx:
            idx = self._getNewObject()
        idx.name = self.data(self.index(row, 0))
        idx.columns = self.data(self.index(row, 1), Qt.UserRole)
        return idx

    def getIndexes(self):
        return [
            idx
            for idx in self.getObjectIter()
        ]
