""""
================================================================================
Create a label+entry row frame, with optional file open browse button.
This is a separate module because it can save code in other programs too.
Caller (or callbacks here): retain returned linked var while row is in use;

Augmented dec-2016, post PP4E:
1) The browse button, if enabled, can now pick either file or folder,
not just file (folders were introduced for Grep dialog in PyEdit)
2) Now sets either title or message in dialog (on Mac OS X, the latter is
required and the first is ignored; On Windows/Linux, the latter is an error)
3) Stretch initial entry width to be 2 * label width, instead of using
platform default (else often too narrow without user resizing)
================================================================================
"""

import sys
from tkinter import *                                # widgets and presets
from tkinter.filedialog import askopenfilename       # file selector dialog
from tkinter.filedialog import askdirectory          # folder selector dialog

def makeFormRow(parent, label, width=15,
                browse=True, extend=False, folder=False, app=''):
    """
    build one row in parent: label+entry, with an optional
    file/folder browse button configured by last 4 arguments; 
    """
    var = StringVar()
    row = Frame(parent)
    lab = Label(row, text=label + '?', relief=RIDGE,  width=width)
    ent = Entry(row, relief=SUNKEN, textvariable=var, width=width*2)

    row.pack(fill=X)                                  # uses packed row frames
    lab.pack(side=LEFT)                               # and fixed-width labels
    ent.pack(side=LEFT, expand=YES, fill=X)           # or use grid(row, col)

    if browse:
        btn = Button(row, text='Browse...')
        btn.pack(side=RIGHT)

        # don't raise root above subject parent, do use slidedowns on Mac
        askargs = dict(parent=parent)

        # portability assist: Mac ignores title, Windows fails on message 
        prompt = label if not app else (app + ': ' + label)
        if sys.platform.startswith('darwin'):
            askargs.update(dict(message=prompt))      # Mac OS X
        else:
            askargs.update(dict(title=prompt))        # Windows/Linux

        asker = askopenfilename if not folder else askdirectory
        if not extend:
            btn.config(command=lambda:
                [var.set(asker(**askargs) or var.get()),      # 2-action combo
                 parent.focus_force()] )                      # refocus for Mac
        else:
            btn.config(command=lambda:
                [var.set(var.get() + ' ' + asker(**askargs)),
                 parent.focus_force()] )
    return var