from flask import has_request_context, flash
from datetime import datetime
from shutil import copy2

from advlabdb import app, db
from advlabdb.models import (
    Part,
    Student,
    Group,
    PartStudent,
    Experiment,
    GroupExperiment,
    Appointment,
    Semester,
    Program,
    SemesterExperiment,
    Assistant,
    User,
)
from advlabdb.exceptions import DataBaseImportException


def importFromFile(filePath):
    if filePath[-4:] != ".txt":
        raise DataBaseImportException(
            "The import file has to be a text file with txt extention (.txt at the end of the filename)!"
        )

    semesters = {}
    parts = {}
    students = {}
    groups = {}
    partStudents = {}
    experiments = {}
    groupExperiments = {}
    appointments = {}

    with open(filePath, "r") as f:  # encoding="iso-8859-15"
        if has_request_context():
            show = flash
        else:
            show = print

        show("Reading file...")

        expectingTable = True
        readHeader = False

        activeDict = None

        for line in f:
            line = line[:-1]

            if not line:
                expectingTable = True
                continue

            if expectingTable:
                if line[0] == "#":
                    expectingTable = False
                    tableName = line[1:]

                    if tableName == "Semester":
                        activeDict = semesters
                    elif tableName == "Part":
                        activeDict = parts
                    elif tableName == "Student":
                        activeDict = students
                    elif tableName == "Group":
                        activeDict = groups
                    elif tableName == "PartStudent":
                        activeDict = partStudents
                    elif tableName == "Experiment":
                        activeDict = experiments
                    elif tableName == "GroupExperiment":
                        activeDict = groupExperiments
                    elif tableName == "Appointment":
                        activeDict = appointments
                    else:
                        raise DataBaseImportException(f"{tableName} is not a valide table name!")

                    readHeader = True
                    continue
                else:
                    raise DataBaseImportException(f"Expected a Table name starting with # but got this line: {line}")

            cells = line.split("\t")

            if readHeader:
                readHeader = False
                activeDict["_header"] = cells

                for cell in cells:
                    activeDict[cell] = []

                continue

            cellsLen = len(cells)
            if cellsLen == len(activeDict["_header"]):
                for i in range(cellsLen):
                    activeDict[activeDict["_header"][i]].append(cells[i])
            else:
                raise DataBaseImportException(
                    f"The number of header cells is not equal to the number of row cells in row {cells}!"
                )

    db.session.rollback()
    with db.session.begin():
        # Semester
        show("Semester...")

        if len(semesters["label"]) * len(semesters["year"]) != 1:
            raise DataBaseImportException("Only one semester is allowed in an import file!")

        semesterLabel = semesters["label"][0]
        semesterYear = int(semesters["year"][0])
        dbSemester = Semester.query.filter(Semester.label == semesterLabel, Semester.year == semesterYear).first()

        if not dbSemester:
            raise DataBaseImportException(
                f"{semesterLabel}{semesterYear} does not exist in the database! Please make sure that you create the semester from the web interface first."
            )

        # Part
        show("Part...")

        dbParts = {}
        for i, id in enumerate(parts["id"]):
            id = int(id)
            partNumber = int(parts["number"][i])
            partProgramLabel = parts["program_label"][i]
            dbPart = Part.query.filter(
                Part.number == partNumber,
                Part.program.has(Program.label == partProgramLabel),
                Part.semester == dbSemester,
            ).first()

            if not dbPart:
                raise DataBaseImportException(
                    f"Part with number {partNumber} and program_label {partProgramLabel} does not exist in the database! Please make sure that you create parts from the web interface first."
                )

            dbParts[id] = dbPart

        # Student
        show("Student...")

        dbStudents = {}
        for i, studentNumber in enumerate(students["student_number"]):
            studentNumber = int(studentNumber)
            dbStudent = Student.query.filter(Student.student_number == studentNumber).first()

            if not dbStudent:
                dbStudent = Student(
                    student_number=studentNumber,
                    first_name=students["first_name"][i],
                    last_name=students["last_name"][i],
                    uni_email=students["uni_email"][i],
                    contact_email=students["contact_email"][i] or None,
                    bachelor_thesis=students["bachelor_thesis"][i] or None,
                    bachelor_thesis_work_group=students["bachelor_thesis_work_group"][i] or None,
                    note=students["note"][i] or None,
                )
                db.session.add(dbStudent)
            else:
                dbStudent.contact_email = students["contact_email"][i] or None
                dbStudent.bachelor_thesis = students["bachelor_thesis"][i] or None
                dbStudent.bachelor_thesis_work_group = students["bachelor_thesis_work_group"][i] or None
                dbStudent.note = students["note"][i] or None

            dbStudents[studentNumber] = dbStudent

        # Group
        show("Group...")

        dbGroups = {}
        for i, id in enumerate(groups["id"]):
            id = int(id)
            dbGroup = Group(
                number=int(groups["number"][i]),
                program=Program.query.filter(Program.label == groups["program_label"][i]).first(),
                semester=dbSemester,
            )
            db.session.add(dbGroup)
            dbGroups[id] = dbGroup

        # PartStudent
        show("PartStudent...")

        for i, studentNumber in enumerate(partStudents["student_number"]):
            studentNumber = int(studentNumber)
            dbPartStudent = PartStudent.customInit(
                student=dbStudents[studentNumber],
                part=dbParts[int(partStudents["part_id"][i])],
                group=dbGroups[int(partStudents["group_id"][i])],
            )
            db.session.add(dbPartStudent)

        # Experiment
        show("Experiment...")

        dbSemesterExperiments = {}
        for i, id in enumerate(experiments["id"]):
            id = int(id)
            experimentNumber = int(experiments["number"][i])
            experimentProgram = Program.query.filter(Program.label == experiments["program_label"][i]).first()
            dbExperiment = Experiment.query.filter(
                Experiment.number == experimentNumber, Experiment.program == experimentProgram
            ).first()

            if not dbExperiment:
                raise DataBaseImportException(
                    f"Experiment with number {experimentNumber} and program {experimentProgram.repr()} does not exist in the database. Please make sure that experiments are created from the web interface."
                )

            dbSemesterExperiment = SemesterExperiment.query.filter(
                SemesterExperiment.experiment == dbExperiment, SemesterExperiment.semester == dbSemester
            ).first()

            if not dbSemesterExperiment:
                raise DataBaseImportException(
                    f"No semester experiment exists in the database to the experiment with number {experimentNumber} and program {experimentProgram.repr()}. Please make sure that semester experiments are created in the web interface. The problem might be that the experiment was not active while creating a new semester"
                )

            dbSemesterExperiments[id] = dbSemesterExperiment

        # GroupExperiment
        show("GroupExperiment...")

        dbGroupExperiments = {}
        for i, id in enumerate(groupExperiments["id"]):
            id = int(id)
            dbGroupExperiment = GroupExperiment.customInit(
                semester_experiment=dbSemesterExperiments[int(groupExperiments["experiment_id"][i])],
                group=dbGroups[int(groupExperiments["group_id"][i])],
            )
            db.session.add(dbGroupExperiment)
            dbGroupExperiments[id] = dbGroupExperiment

        # Appointment
        show("Appointment...")

        for i, date in enumerate(appointments["date"]):
            assistantEmail = appointments["assistant_email"][i]
            assistant = Assistant.query.filter(Assistant.user.has(User.email == assistantEmail)).first()

            if not assistant:
                raise DataBaseImportException(
                    f"Assistant with email {email} does not exist in the database! Please make sure that you create assistants in the web interface."
                )

            dbAppointment = Appointment.customInit(
                date=datetime.strptime(date, "%d.%m.%Y").date(),
                special=bool(int(appointments["special"][i])),
                group_experiment=dbGroupExperiments[int(appointments["group_experiment_id"][i])],
                assistant=assistant,
            )
            db.session.add(dbAppointment)

        # Backup
        # TODO: Check existing dirs
        src = "db/advLab.db"
        dest = f"db/backups/before_{dbSemester.repr()}_import_{datetime.now().strftime('%d_%m_%Y_%H_%M_%S')}.db"
        copy2(src, dest)

        show(f"Made a backup of the database before the import at {dest}")

        # Auto commit from the transaction context
    
    src = "db/advLab.db"
    dest = f"db/backups/after_{dbSemester.repr()}_import_{datetime.now().strftime('%d_%m_%Y_%H_%M_%S')}.db"
    copy2(src, dest)

    show(f"Made a backup of the database after the import at {dest}")

    show("\nImport done!")
    show("Please check that everything worked as expected. Restore the database backup otherwise!")