frontend/src/planner/projectTimeline.ts

import { format, parseISO } from "date-fns";

export interface ProjectBarSegment {
  startIndex: number;
  endIndex: number;
  className: string;
  label: string;
}

export function buildProjectBarSegment(
  dayDates: Date[],
  startDate: string,
  endDate: string,
  name: string,
  tentative: boolean,
  showTentative: boolean,
): ProjectBarSegment | null {
  if (!showTentative && tentative) return null;

  const rangeStart = startDate;
  const rangeEnd = endDate;
  let startIndex = -1;
  let endIndex = -1;

  dayDates.forEach((day, index) => {
    const key = format(day, "yyyy-MM-dd");
    if (key < rangeStart || key > rangeEnd) return;
    if (startIndex === -1) startIndex = index;
    endIndex = index;
  });

  if (startIndex === -1) return null;

  return {
    startIndex,
    endIndex,
    className: tentative ? "project-bar tentative" : "project-bar",
    label: name,
  };
}

export function projectBarStyle(segment: ProjectBarSegment, totalDays: number): { left: string; width: string } {
  const span = segment.endIndex - segment.startIndex + 1;
  return {
    left: `${(segment.startIndex / totalDays) * 100}%`,
    width: `${(span / totalDays) * 100}%`,
  };
}

export function overlapsVisibleRange(
  startDate: string,
  endDate: string,
  viewStart: Date,
  viewEnd: Date,
): boolean {
  const projStart = parseISO(startDate);
  const projEnd = parseISO(endDate);
  return projStart < viewEnd && projEnd >= viewStart;
}