#!/usr/bin/python

# Regdel, a ncurses inteface to ledger
#
# copyright (c) 2016 Guillaume Chereau <guillaume@noctua-software.com>
#
# Regdel 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 3 of the License, or (at your option) any later
# version.
#
# Regdel is distributed in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
# A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along with
# regdel.  If not, see <http://www.gnu.org/licenses/>.

import itertools
from collections import namedtuple
import curses
import datetime
import subprocess
import sys
import csv

LineInfo = namedtuple('LineInfo', ['color_id', 'color', 'bg', 'attr'])

# XXX: how to clean this up?
LINE_INFOS = {
    "bar": LineInfo(0, curses.COLOR_WHITE, curses.COLOR_BLUE, curses.A_BOLD),
    "cursor": LineInfo(0, curses.COLOR_WHITE, curses.COLOR_GREEN, curses.A_BOLD),
    "date": LineInfo(0, curses.COLOR_BLUE, -1, 0),
    "value_pos": LineInfo(0, curses.COLOR_GREEN, -1, 0),
    "value_neg": LineInfo(0, curses.COLOR_RED, -1, 0),
}

KEY_MAP = {
    ord('k'):           "PREV_LINE",
    ord('j'):           "NEXT_LINE",
    curses.KEY_UP:      "PREV_LINE",
    curses.KEY_DOWN:    "NEXT_LINE",
    ord('q'):           "QUIT",
    ord('c'):           "CURRENCY",
    ord('\n'):          "SELECT",
    ord(' '):           "NEXT_PAGE",
    ord('g'):           "FIRST_LINE",
    curses.KEY_HOME:    "FIRST_LINE",
    ord('G'):           "LAST_LINE",
    curses.KEY_END:     "LAST_LINE",
}

def clamp(x, a, b): return min(max(x, a), b)

def ledger(path, cmd, query="", form=None, currency=None, options=None):
    args = ['ledger', '-f', path]
    args += [cmd]
    if options: args += options
    form_keys = None
    if isinstance(form, dict):
        form_keys = form.keys()
        form = form.values()
    if form is not None:
        form = ','.join('%(quoted({}))'.format(x) for x in form)
        form += '\n\n'
        args += ['--format', form]
    if currency is not None:
        args += ['-X', currency]
    args += [query]
    out = subprocess.check_output(args)
    out = out.split('\n\n' if form else '\n')
    if form is not None:
        out = [x for x in csv.reader(out)]
        if form_keys is not None:
            out = [{k:v for k, v in zip(form_keys, x)} for x in out]
    return out


class View(object):

    def __init__(self, app, win):
        self.app = app
        self.lineno = 0
        h, w = win.getmaxyx()
        self.full = win
        self.win = curses.newwin(h - 1, w, 1, 0)
        self.bar = curses.newwin(1, w, 0, 0)
        self.bar.bkgdset(' ', self.get_attr('bar'))
        self.w = w
        self.h = h - 1
        self.offset = 0

    def get_attr(self, line):
        if line in LINE_INFOS:
            inf = LINE_INFOS[line]
            return curses.color_pair(inf.color_id) | inf.attr
        else:
            return 0

    def refresh(self):
        # XXX: why - 2 ??
        self.lineno = clamp(self.lineno, 0, len(self.lines) - 2)

        # Make sure lineno is visible (ie: offset < lineno < offset + h)
        self.offset = min(self.offset, self.lineno)
        self.offset = max(self.offset, self.lineno - self.h + 1)

        self.win.clear()
        for i in range(self.win.getmaxyx()[0]):
            self.win.move(i, 0)
            self.render(self.win, i + self.offset)
        self.bar.clear()
        self.bar.move(0, 0)
        self.render_bar(self.bar)
        self.win.refresh()
        self.bar.refresh()

    def select(self, i):
        return None

    def toggle_currency(self):
        return

    def render_bar(self, win):
        return


class AccountsView(View):
    def __init__(self, app, win):
        super(AccountsView, self).__init__(app, win)
        lines = ledger(app.path, 'accounts')
        accounts = []
        for line in lines:
            for i in range(len(line.split(':'))):
                a = ':'.join(line.split(':')[:i+1])
                if a not in accounts: accounts.append(a)
        self.lines = accounts

    def render(self, win, i):
        if i >= len(self.lines): return
        line = self.lines[i]
        cur = 'cursor' if i == self.lineno else None
        win.addstr(line, self.get_attr(cur or 'account'))

    def render_bar(self, win):
        win.addstr("Accounts")

    def select(self, i):
        return RegView(self.app, self.full, self.lines[i])

class RegView(View):
    def __init__(self, app, win, account):
        assert isinstance(account, str)
        super(RegView, self).__init__(app, win)
        self.account = account
        self.currency = None
        self.update()

    def update(self):
        form = dict(date='date', payee='payee',
                    amount='scrub(display_amount)',
                    commodity='commodity(scrub(display_amount))',
                    total='scrub(display_total)',
                    account='display_account')
        self.lines = ledger(self.app.path, 'reg', self.account,
                            form=form, currency=self.currency,
                            options=['--effective', '-S', 'date'])

    def render(self, win, i):
        if i >= len(self.lines): return
        line = self.lines[i]
        if not line: return
        cur = 'cursor' if i == self.lineno else None
        win.addstr("{} ".format(line['date']), self.get_attr(cur or 'date'))
        win.addstr("{:<20.20} ".format(line['payee']), self.get_attr(cur or 'payee'))
        win.addstr("{:<20.20} ".format(line['account']), self.get_attr(cur or 'payee'))
        win.addstr("{:>20} ".format(line['amount']), self.get_attr(cur or 'value_pos'))
        tot = "ERR"
        for t in line['total'].split('\n'):
            if line['commodity'] in t:
                tot = t
        win.addstr("{:>20} ".format(tot), self.get_attr(cur))

    def render_bar(self, win):
        win.addstr(self.account)
        if self.currency:
            win.addstr(" ({})".format(self.currency))

    def toggle_currency(self):
        if self.currency is None:
            self.currency = 'HKD'
        else:
            self.currency = None
        self.update()

    def select(self, i):
        line = self.lines[i]
        query = '{} @{}'.format(self.account, line['payee'])
        date = datetime.datetime.strptime(line['date'], '%Y/%m/%d').date()
        enddate = date + datetime.timedelta(1)
        out = ledger(self.app.path, 'print', query,
                     options=['--raw',
                              '--effective',
                              '--begin', "{}".format(date),
                              '--end', "{}".format(enddate)])
        return TransactionView(self.app, self.full, out)

class TransactionView(View):
    def __init__(self, app, win, lines):
        super(TransactionView, self).__init__(app, win)
        self.lines = lines
    def render(self, win, i):
        if i >= len(self.lines): return
        line = self.lines[i]
        cur = 'cursor' if i == self.lineno else None
        win.addstr(line, self.get_attr(cur))
    def select(self, i):
        txt = self.lines[i].split()[0]
        return RegView(self.app, self.full, txt)


class App:
    def __init__(self, path, scr):
        self.path = path
        self.scr = scr
        self.view = AccountsView(self, self.scr)
        self.views = [self.view]

    def process(self, req):
        #XXX: auto call refresh if lineno or offset changed.
        step = 0
        if req == "QUIT":
            self.views.pop()
            if not self.views: return True
            self.view = self.views[-1]
            self.view.refresh()
        if req == "CURRENCY":
            self.view.toggle_currency()
            self.view.refresh()
        if req == "NEXT_LINE": step = +1
        if req == "PREV_LINE": step = -1
        if req == "NEXT_PAGE":
            step = self.view.win.getmaxyx()[0]
            self.view.offset += self.view.win.getmaxyx()[0]
        if req == "FIRST_LINE":
            self.view.lineno = 0
            self.view.offset = 0
            self.view.refresh()
        if req == "LAST_LINE":
            self.view.lineno = len(self.view.lines)
            self.view.refresh()
        if req == "SELECT":
            view = self.view.select(self.view.lineno)
            if view:
                self.views.append(view)
                self.view = view
                self.view.refresh()
        self.view.lineno += step
        if req == "MAIN" or step != 0:
            self.view.refresh()

    def run(self):
        self.process("MAIN")
        while True:
            c = self.scr.getch()
            req = KEY_MAP.get(c)
            if self.process(req): break

if len(sys.argv) != 2:
    print "USAGE: regdel <ledger-file>"
    sys.exit(-1)

curses.initscr()
curses.start_color()
curses.use_default_colors()

def start(scr):
    for i, key in enumerate(LINE_INFOS):
        inf = LINE_INFOS[key]
        color_id = i + 1
        curses.init_pair(color_id, inf.color, inf.bg)
        LINE_INFOS[key] = inf._replace(color_id=color_id)

    app = App(sys.argv[1], scr)
    app.run()

curses.wrapper(start)