wrma_billing.js

// refactored by Rushabh Mehta
// original script https://gist.github.com/rmehta/5a7dbf05494990b838f8

cur_frm.add_fetch('item_code','amount_allocated_on_permit',
  'amount_allocated_on_permit');

window.naivasha = {
  recalculate: function(doc, child_doctype, child_name) {
    if(!doc) {
      doc = cur_frm.doc;
      child_doctype = cur_frm.doc.items[0].doctype;
      child_name = cur_frm.doc.items[0].name;
    }
    setTimeout(function() {
      frappe.after_ajax(function() {
        naivasha._recalculate(doc, child_doctype, child_name);
      }, 1000);
    })
  },
  _recalculate: function(doc, child_doctype, child_name) {
    var row = frappe.model.get_doc(child_doctype, child_name);

    if (!row.amount_allocated_on_permit || !row.consumption) {
      return;
    }

    if(cur_frm.cur_grid) {
      cur_frm.cur_grid.hide_form();
    }

    if(!row.water_use_fee) {
      row.water_use_fee = "Normal (Ksh 0.50)";
    }

    naivasha.set_accounting_period(row, doc);

    // rate
    row.rate = naivasha.get_rate(row.water_use_fee);

    row.total_amount_allocated_for_accounting_period =
      flt(row.amount_allocated_on_permit) * flt(row.number_of_days);
    row.total_amount_lawfully_used =
       Math.min(row.total_amount_allocated_for_accounting_period,
         flt(row.consumption));
    if (row.rate == 0.5) {
  		row.volume_of_water_charged_at_the_selected_fee =
  		Math.min(flt(row.number_of_days) * 300, flt(row.consumption)); // 50 cent
    } else if (row.rate == 0.75) {
      row.volume_of_water_charged_at_the_selected_fee =
        Math.max(0, flt(row.total_amount_lawfully_used) -
          Math.min(flt(row.number_of_days) * 300, flt(row.consumption)));
        // 75 cent
    } else if (row.rate == 1.0) {
      row.volume_of_water_charged_at_the_selected_fee =
        flt(row.consumption) - flt(row.total_amount_lawfully_used);
    } else {
      row.volume_of_water_charged_at_the_selected_fee = 0;
    }

    row.qty =  row.volume_of_water_charged_at_the_selected_fee;
    row.amount = row.rate * row.qty;
    row.description = row.item_name + ", " + row.water_use_fee;

    if (row.rate == 0.5) {
      naivasha.make_additional_rows(row);
    }

    cur_frm.refresh_field("items");
  },
  set_accounting_period: function(row, doc) {
    if (!row.start_date_of_accounting_period)
      row.start_date_of_accounting_period =
        doc.start_date_of_accounting_period;

    if (!row.end_date_of_accounting_period)
      row.end_date_of_accounting_period =
        doc.end_date_of_accounting_period;

    // days
    row.number_of_days = moment(row.end_date_of_accounting_period)
      .diff(row.start_date_of_accounting_period, "day");

  },
  make_additional_rows: function(row) {
    var row1 = naivasha.get_dependant_row(row, 1);

    var fields_to_copy = ["consumption", "item_name",
      "item_code", "amount_allocated_on_permit", "number_of_days",
      "total_amount_allocated_for_accounting_period",
      "total_amount_lawfully_used"];

    // row 1
    row1.water_use_fee = "High (Ksh 0.75)";
    row1.rate = 0.75;
    for(var i=0; i < fields_to_copy.length; i++) {
      row1[fields_to_copy[i]] = row[fields_to_copy[i]];
    }

    row1.volume_of_water_charged_at_the_selected_fee =
      Math.max(0, row1.total_amount_lawfully_used - Math.min(row1.number_of_days * 300, row1.consumption)); // 75 cent
    row1.qty =  row1.volume_of_water_charged_at_the_selected_fee;
    row1.amount = row1.rate * row1.qty;
    row1.description = row1.item_name + ", " + row1.water_use_fee;

    // row 2
    var row2 = naivasha.get_dependant_row(row, 2);
    row2.water_use_fee = "Penalty (Ksh 1.00)";
    row2.rate = 1.0;

    for(var i=0; i < fields_to_copy.length; i++) {
      row2[fields_to_copy[i]] = row[fields_to_copy[i]];
    }

    row2.volume_of_water_charged_at_the_selected_fee =
      row2.consumption - row2.total_amount_lawfully_used;
    row2.qty =  row2.volume_of_water_charged_at_the_selected_fee;
    row2.amount = row2.rate * row2.qty;
    row2.description = row2.item_name + ", " + row2.water_use_fee;
  },
  get_rate: function(text) {
    if (text != null) {
      var i = text.indexOf('Ksh');
      if (i > 0) {
        text = text.split("Ksh ")[1].split(")")[0];
        return parseFloat(text);
      }
    }
    return -1.0;
  },
  get_dependant_row: function(row, seq) {
    // returns next row or creates a new one
    for (i = 0; i < cur_frm.doc.items.length; i++) {
      var row1 = cur_frm.doc.items[i];
      if (row1.idx == row.idx + seq) {
        return row1;
      }
    }

    // add new row
    return cur_frm.add_child("items");
  }

}

frappe.ui.form.on("Sales Invoice", {
  onload: function(frm) {
    if(!frm.doc.start_date_of_accounting_period) {
      frm.set_value("start_date_of_accounting_period",
        moment().startOf("month").format());
    }
    if(!frm.doc.end_date_of_accounting_period) {
      frm.set_value("end_date_of_accounting_period",
        moment().endOf("month").format());
    }
  },
  entries_add: function(frm, child_doctype, child_name) {
    var row = frappe.model.get_doc(child_doctype, child_name);
    naivasha.set_accounting_period(row, frm.doc);
    cur_frm.refresh_field("items");
  },
  entries_on_form_rendered: function(frm) {
    var cur_grid = cur_frm.cur_grid;
    var row = cur_grid.doc;
    var ro = row.water_use_fee
      && naivasha.get_rate(row.water_use_fee) != 0.5;
    cur_grid.grid.get_docfield(
      "total_amount_allocated_for_accounting_period").read_only = ro;
    cur_grid.grid.get_docfield("consumption").read_only = ro;
    cur_grid.refresh_field("total_amount_allocated_for_accounting_period");
    cur_grid.refresh_field("consumption");
  }
});

frappe.ui.form.on("Sales Invoice Item", {
  item_code: function(frm, child_doctype, child_name) {
    naivasha.recalculate(frm.doc, child_doctype, child_name)
  },
  start_date_of_accounting_period: function(frm, child_doctype, child_name) {
    naivasha.recalculate(frm.doc, child_doctype, child_name)
  },
  end_date_of_accounting_period: function(frm, child_doctype, child_name) {
    naivasha.recalculate(frm.doc, child_doctype, child_name)
  },
  water_use_fee: function(frm, child_doctype, child_name) {
    naivasha.recalculate(frm.doc, child_doctype, child_name)
  },
  consumption: function(frm, child_doctype, child_name) {
    naivasha.recalculate(frm.doc, child_doctype, child_name)
  },
})