try:
    import Tkinter
except ImportError:
    import tkinter as Tkinter

class Application:
    "Graphical user interface for a checkbook register application"

    def __init__(self):
        # Set up register
        from register import Register
        self.register = Register()
        self.currentTransaction = None

        # Create the overall frame
        self.frame = Tkinter.Frame()
        self.top = self.frame.winfo_toplevel()
        self.top.title("Checkbook Register")
        # Whether a frame/widget expands when the top level
        # window is resized depends on two factors: (1) whether
        # the containing (or master) frame has a non-zero weight,
        # and (2) whether the frame is "sticky" to the master.
        # There is only one frame under the top level, so we
        # give column 0, row 0 a weight of 1 so that the frame
        # will expand and contract with the top level window
        self.top.columnconfigure(0, weight=1)
        self.top.rowconfigure(0, weight=1)
        # There are two frames under the main frame: the data
        # entry widget and the register display.  Both frames
        # should expand width-wise when the window expands, so
        # we give column 0 a weight of 1.  The data entry frame
        # does not need to expand vertically, so we do not
        # bother changing the weight for row 0 (thereyby using
        # the default weight of 0).  The register display frame
        # should expand vertically, so we give row 1 a weight
        # of 1.
        self.frame.columnconfigure(0, weight=1)
        self.frame.grid(row=0, column=0, sticky="news")
        # Note that we ask for "stickiness" in all four directions
        # of north, south, east and west.  So expansion/contraction
        # either horizontally or vertically change the size of
        # this frame.
        self.frame.rowconfigure(1, weight=1)

        # Create frame containing data entry widgets
        f = Tkinter.Frame(master=self.frame)
        f.grid(row=0, column=0, sticky="ew")
        # Note that we only ask for "stickiness" in two directions:
        # east and west.  So only expansion/contraction in the
        # horizontal direction will change the size of this frame.
        self._makeDataEntryWidgets(f)

        # Create text widget for displaying transactions
        import tkFont
        self.font = tkFont.Font(family="courier", size=12)
        self.boldFont = tkFont.Font(family="courier", size=12,
                        weight="bold")
        self.text = Tkinter.Text(master=self.frame,
                        width=100,
                        wrap="none",
                        font=self.font)
        self.text.grid(row=1, column=0, sticky="news")
        self.text.bind("<ButtonRelease-1>", self._textClick)
        self.showRegister()

    def _makeDataEntryWidgets(self, f):
        # Create list of buttons for initiating actions
        f.columnconfigure(0, weight=1)
        buttonFrame = Tkinter.Frame(master=f, pady=5)
        buttonFrame.grid(row=1, column=0, sticky="e")
        buttonRemove = Tkinter.Button(master=buttonFrame, width=8,
                        text="Remove",
                        command=self._cbRemove)
        buttonRemove.grid(row=0, column=0, padx=5)
        buttonUpdate = Tkinter.Button(master=buttonFrame, width=8,
                        text="Update",
                        command=self._cbUpdate)
        buttonUpdate.grid(row=0, column=1, padx=5)
        buttonComplete = Tkinter.Button(master=buttonFrame, width=8,
                        text="Complete",
                        command=self._cbComplete)
        buttonComplete.grid(row=0, column=2, padx=5)
        buttonAdd = Tkinter.Button(master=buttonFrame, width=8,
                        text="Add",
                        command=self._cbAdd)
        buttonAdd.grid(row=0, column=3, padx=5)

        # Create transaction data entry widgets
        widgetFrame = Tkinter.Frame(master=f, pady=5, padx=5)
        widgetFrame.grid(row=0, column=0, sticky="ew")
        widgetFrame.columnconfigure(1, weight=1)
        l = Tkinter.Label(master=widgetFrame, text="Transaction Type:")
        l.grid(row=0, column=0, sticky="e")
        typeFrame = Tkinter.Frame(master=widgetFrame)
        typeFrame.grid(row=0, column=1, sticky="w")
        self.typeVar = Tkinter.StringVar(typeFrame)
        b = Tkinter.Radiobutton(master=typeFrame, text="Deposit",
                        value="deposit",
                        variable=self.typeVar)
        b.grid(row=0, column=0)
        b = Tkinter.Radiobutton(master=typeFrame, text="Withdrawal",
                        value="withdrawal",
                        variable=self.typeVar)
        b.grid(row=0, column=1)
        self.typeVar.set("deposit")
        self.number = self._addEntry(widgetFrame, 1, "Number")
        self.date = self._addEntry(widgetFrame, 2, "Date")
        self.cDate = self._addEntry(widgetFrame, 3, "Completion Date")
        self.desc = self._addEntry(widgetFrame, 4, "Description")
        self.amount = self._addEntry(widgetFrame, 5, "Amount")

    def _addEntry(self, f, row, label):
        l = Tkinter.Label(master=f, text=label + ":")
        l.grid(row=row, column=0, sticky="e")
        e = Tkinter.Entry(master=f)
        e.grid(row=row, column=1, sticky="ew")
        return e

    def _cbRemove(self):
        "Callback function when Remove button is pressed"
        if self.currentTransaction is None:
            self.complain("No selected transaction")
            return
        self.register.remove(self.currentTransaction)
        self.currentTransaction = NOne
        self.showRegister()
        self.showCurrentTransaction()

    def _cbUpdate(self):
        "Callback function when Update button is pressed"
        if self.currentTransaction is None:
            self.complain("No selected transaction")
            return
        try:
            number = self.getNumber(emptyOkay=True)
            date = self.getDate(emptyOkay=True)
            cDate = self.getCompletionDate(emptyOkay=True)
            desc = self.getDescription(emptyOkay=True)
            amt = self.getAmount(emptyOkay=True)
            self.currentTransaction.update(number=number,
                            date=date,
                            completionDate=cDate,
                            description=desc,
                            amount=amt)
        except ValueError as s:
            self.complain(s)
            return
        self.showRegister()
        self.showCurrentTransaction()

    def _cbComplete(self):
        "Callback function when Complete button is pressed"
        if self.currentTransaction is None:
            self.complain("No selected transaction")
            return
        try:
            cDate = self.getCompletionDate()
            amt = self.getAmount()
            self.currentTransaction.complete(cDate, amt)
        except ValueError as s:
            self.complain(s)
            return
        self.showRegister()
        self.showCurrentTransaction()

    def _cbAdd(self):
        "Callback function when Add button is pressed"
        try:
            number = self.getNumber(emptyOkay=True)
            date = self.getDate()
            cDate = self.getCompletionDate(emptyOkay=True)
            desc = self.getDescription()
            amt = self.getAmount()
        except ValueError as s:
            self.complain(s)
            return
        from transaction import Transaction
        t = Transaction(date, desc, amt,
                number=number, completionDate=cDate)
        self.register.add(t)
        self.currentTransaction = t
        self.showRegister()
        self.showCurrentTransaction()

    def getNumber(self, emptyOkay=False):
        "Get value from 'Number' widget"
        data = self.number.get().strip()
        if not data:
            if emptyOkay:
                return None
            else:
                raise ValueError("Number is missing")
        return data

    def getDate(self, emptyOkay=False):
        "Get value from 'Date' widget"
        return self._getDate(self.date, "Date", emptyOkay)

    def getCompletionDate(self, emptyOkay=False):
        "Get value from 'Completion Date' widget"
        return self._getDate(self.cDate, "Completion date", emptyOkay)

    def _getDate(self, widget, which, emptyOkay):
        data = widget.get().strip()
        if not data:
            if emptyOkay:
                return None
            else:
                raise ValueError("%s is missing" % which)
        fields = data.split('-')
        if len(fields) != 3:
            raise ValueError("%s format must be YYYY-MM-DD" % which)
        try:
            year = int(fields[0])
            month = int(fields[1])
            day = int(fields[2])
        except ValueError:
            raise ValueError("%s values must be integers" % which)
        if year < 50:
            year += 2000
        elif year < 100:
            year += 1900
        from datetime import date
        return date(year, month, day)

    def getDescription(self, emptyOkay=False):
        "Get value from 'Description' widget"
        data = self.desc.get().strip()
        if not data:
            if emptyOkay:
                return None
            else:
                raise ValueError("Description is missing")
        return data

    def getAmount(self, emptyOkay=False):
        "Get value from 'Amount' widget"
        data = self.amount.get().strip()
        if not data:
            if emptyOkay:
                return None
            else:
                raise ValueError("Amount is missing")
        amt = float(data)
        type = self.typeVar.get()
        if type == "withdrawal":
            amt = -amt
        return amt

    def complain(self, msg):
        "Display an error message and wait for user to hit Okay"
        from tkMessageBox import showerror
        showerror(title="Error", message=msg)

    def showRegister(self):
        "Display register in text widget"
        from StringIO import StringIO
        f = StringIO()
        self.register.printStatement(f)
        self.text.delete("1.0", "end")
        self.text.insert("1.0", f.getvalue())
        self.text.tag_add("header", "1.0", "1.0 lineend")
        self.text.tag_configure("header", font=self.boldFont)
        if self.currentTransaction is not None:
            n = self.register.transactions.index(
                        self.currentTransaction)
            tag = str(n + 2) + ".0"    # +1 for Tk text being 1-based
                        # +1 for first line being header
            self.text.tag_add("current", tag, tag + " lineend")
            self.text.tag_configure("current", background="gray")
    
    def showCurrentTransaction(self):
        "Display current transaction values in input widgets"
        if self.currentTransaction is None:
            # Shoud we erase what's there?
            return
        t = self.currentTransaction
        if t.number is None:
            self._updateEntry(self.number, "")
        else:
            self._updateEntry(self.number, str(t.number))
        if t.date is None:
            self._updateEntry(self.date, "")
        else:
            self._updateEntry(self.date, str(t.date))
        if t.completionDate is None:
            self._updateEntry(self.cDate, "")
        else:
            self._updateEntry(self.cDate, str(t.completionDate))
        if t.description is None:
            self._updateEntry(self.desc, "")
        else:
            self._updateEntry(self.desc, str(t.description))
        if t.amount < 0:
            self.typeVar.set("withdrawal")
            self._updateEntry(self.amount, "%.2f" % -t.amount)
        else:
            self.typeVar.set("deposit")
            self._updateEntry(self.amount, "%.2f" % t.amount)

    def _updateEntry(self, e, value):
        e.delete(0, "end")
        e.insert(0, value)

    def _textClick(self, event):
        place = self.text.index("@%d,%d" % (event.x, event.y))
        line, char = place.split('.')
        n = int(line) - 2
        if n < 0 or n >= len(self.register.transactions):
            selected = None
        else:
            selected = self.register.transactions[n]
        if self.currentTransaction is selected:
            return
        if self.currentTransaction:
            self.text.tag_delete("current")
        self.currentTransaction = selected
        self.showCurrentTransaction()
        self.showRegister()

    def run(self):
        "Run the Tk event loop for the graphical user interface"
        self.top.mainloop()

if __name__ == "__main__":
    app = Application()
    app.run()