/*
 *  Copyright 1998-2025 by Northwoods Software Corporation. All Rights Reserved.
 */

/*
 * This is an extension and not part of the main GoJS library.
 * The source code for this is at extensionsJSM/PanelLayoutFlow.ts.
 * Note that the API for this class may change with any version, even point releases.
 * If you intend to use an extension in production, you should copy the code to your own source directory.
 * Extensions can be found in the GoJS kit under the extensions or extensionsJSM folders.
 * See the Extensions intro page (https://gojs.net/latest/intro/extensions.html) for more information.
 */

import * as go from 'gojs';

/**
 * A custom {@link go.PanelLayout} that arranges panel elements in rows or columns.
 * A typical use might be:
 * ```js
 * $(go.Node,
 *   ...
 *   $(go.Panel, "Flow",
 *     ... the elements to be laid out in rows with no space between them ...
 *   )
 *   ...
 * )
 * ```
 * A customized use might be:
 * ```js
 * $(go.Node,
 *   ...
 *   $(go.Panel,
 *     $(PanelLayoutFlow, { spacing: new go.Size(5, 5), direction: 90 }),
 *     ... the elements to be laid out in columns ...
 *   )
 *   ...
 * )
 * ```
 *
 * The {@link direction} property determines whether the elements are arranged in rows (if 0 or 180)
 * or in columns (if 90 or 270).
 *
 * Use the {@link spacing} property to control how much space there is between elements in a row or column
 * as well as between rows or columns.
 *
 * This layout respects the {@link go.GraphObject.visible}, {@link go.GraphObject.stretch},
 * and {@link go.GraphObject.alignment} properties on each element, along with the Panel's
 * {@link go.Panel.defaultStretch}, {@link go.Panel.defaultAlignment}, and {@link go.Panel.padding} properties.
 *
 * If you want to experiment with this extension, try the <a href="../../samples/PanelLayoutFlow.html">Flow PanelLayout</a> sample.
 * @category Layout Extension
 */
export class PanelLayoutFlow extends go.PanelLayout {
  private _direction: number; // only 0 or 180 (rows) or 90 or 270 (columns)
  private _spacing: go.Size; // space between elements and rows/columns
  // these need to go as the Panel.panelLayoutState, because they are computed by measure and later used by arrange
  // lineBreadths = []; // row height or column width, excluding spacing
  // lineLengths = [];  // line length, excluding padding and external spacing

  /**
   * Constructs a PanelLayoutFlow that lays out elements in rows
   * with no space between the elements or between the rows.
   */
  constructor(init?: Partial<PanelLayoutFlow>) {
    super();
    this.name = 'Flow';
    this._direction = 0;
    this._spacing = new go.Size(0, 0);
    if (init) Object.assign(this, init);
  }

  /**
   * Gets or sets the initial direction in which elements are laid out.
   * The value must be 0 or 180, which results in rows, or 90 or 270, which results in columns.
   *
   * The default value is 0, resulting in rows that go rightward.
   * A value of 90 results in columns that go downward.
   *
   * Setting this property does not notify about any changed event,
   * nor does a change in value automatically cause the panel layout to be performed again.
   */
  get direction() {
    return this._direction;
  }
  set direction(d: number) {
    if (d !== 0 && d !== 90 && d !== 180 && d !== 270) throw new Error('bad direction for PanelLayoutFlow: ' + d);
    this._direction = d;
  }

  /**
   * Gets or sets the space between adjacent elements in the panel and the space between adjacent rows or columns.
   *
   * The default value is (0, 0).  The size is in the panel's coordinate system.
   *
   * Setting this property does not notify about any changed event,
   * nor does a change in value automatically cause the panel layout to be performed again.
   */
  get spacing() {
    return this._spacing;
  }
  set spacing(s: go.Size) {
    if (!(s instanceof go.Size)) throw new Error('PanelLayoutFlow.spacing must be a Size');
    this._spacing = s;
  }

  override measure(
    panel: go.Panel,
    width: number,
    height: number,
    elements: Array<go.GraphObject>,
    union: go.Rect,
    minw: number,
    minh: number
  ): void {
    const lineBreadths = [] as Array<number>; // attach properties on panel
    const lineLengths = [] as Array<number>;
    (panel as any).panelLayoutState = { lineBreadths: lineBreadths, lineLengths: lineLengths };
    const pad = panel.padding as go.Margin;
    const wrapx = width + pad.left; // might be Infinity
    const wrapy = height + pad.top;
    let x = pad.left; // account for padding
    let y = pad.top;
    const xstart = x; // remember start
    const ystart = y;
    // assume that measuring is the same for either direction
    if (this.direction === 0 || this.direction === 180) {
      let maxx = x; // track total width
      let rowh = 0; // compute row height
      for (let i = 0; i < elements.length; i++) {
        const elem = elements[i];
        if (!elem.visible) continue;
        this.measureElement(elem, Infinity, height, minw, minh);
        const mb = elem.measuredBounds;
        const marg = elem.margin as go.Margin;
        const gw = marg.left + mb.width + marg.right; // gross size including margins
        const gh = marg.top + mb.height + marg.bottom;
        if (x + gw > wrapx && i > 0) {
          // next row
          lineBreadths.push(rowh); // remember previous row info
          lineLengths.push(x - pad.left);
          y += rowh + this.spacing.height; // advance x and y
          if (y + gh <= wrapy) {
            // next row fits???
            x = xstart + gw + this.spacing.width;
            rowh = gh;
          } else {
            // clipped, assume zero size
            x = xstart;
            rowh = 0;
            break;
          }
        } else {
          // advance x
          x += gw + this.spacing.width;
          rowh = Math.max(rowh, gh);
        }
        maxx = Math.max(maxx, x);
      }
      lineBreadths.push(rowh);
      lineLengths.push(x - pad.left);
      union.width = Math.max(0, Math.min(maxx, wrapx) - pad.left); // don't add padding to union
      union.height = Math.max(0, y + rowh - pad.top);
    } else if (this.direction === 90 || this.direction === 270) {
      let maxy = y;
      let colw = 0;
      for (let i = 0; i < elements.length; i++) {
        const elem = elements[i];
        if (!elem.visible) continue;
        this.measureElement(elem, width, Infinity, minw, minh);
        const mb = elem.measuredBounds;
        const marg = elem.margin as go.Margin;
        const gw = marg.left + mb.width + marg.right;
        const gh = marg.top + mb.height + marg.bottom;
        if (y + gh > wrapy && i > 0) {
          lineBreadths.push(colw);
          lineLengths.push(y - pad.top);
          x += colw + this.spacing.width;
          if (x + gw <= wrapx) {
            y = ystart + gh + this.spacing.height;
            colw = gw;
          } else {
            y = ystart;
            colw = 0;
            break;
          }
        } else {
          y += gh + this.spacing.height;
          colw = Math.max(colw, gw);
        }
        maxy = Math.max(maxy, y);
      }
      lineBreadths.push(colw);
      lineLengths.push(y - pad.top);
      union.width = Math.max(0, x + colw - pad.left);
      union.height = Math.max(0, Math.min(maxy, wrapy) - pad.top);
    }
  }

  private isStretched(horiz: boolean, elt: go.GraphObject, panel: go.Panel): boolean {
    let s = elt.stretch;
    if (s === go.Stretch.Default) s = panel.defaultStretch;
    if (s === go.Stretch.Fill) return true;
    return s === (horiz ? go.Stretch.Vertical : go.Stretch.Horizontal);
  }

  private align(elt: go.GraphObject, panel: go.Panel): go.Spot {
    let a = elt.alignment;
    if (a.isDefault()) a = panel.defaultAlignment;
    if (!a.isSpot()) a = go.Spot.Center;
    return a;
  }

  override arrange(panel: go.Panel, elements: Array<go.GraphObject>, union: go.Rect): void {
    const lineBreadths = (panel as any).panelLayoutState.lineBreadths as Array<number>;
    const lineLengths = (panel as any).panelLayoutState.lineLengths as Array<number>;
    const pad = panel.padding as go.Margin;
    let x = this.direction === 180 ? union.width - pad.right : pad.left;
    let y = this.direction === 270 ? union.height - pad.bottom : pad.top;
    const xstart = x;
    const ystart = y;
    if (this.direction === 0) {
      let row = 0;
      for (let i = 0; i < elements.length; i++) {
        const elem = elements[i];
        if (!elem.visible) continue;
        const mb = elem.measuredBounds;
        const marg = elem.margin as go.Margin;
        const gw = marg.left + mb.width + marg.right;
        // use computed row length to decide whether to wrap, account for error accumulation
        if (x - pad.left > lineLengths[row] - 0.00000005 && i > 0) {
          y += lineBreadths[row++] + this.spacing.height;
          x = xstart;
          if (row === lineLengths.length) row--; // if on last row, stay there
        }
        const lastbr = lineBreadths[row]; // if row was clipped,
        let h = lastbr > 0 ? lastbr - marg.top - marg.bottom : 0; // use zero height
        let ya = lastbr > 0 ? y + marg.top : y; // and stay at same Y point
        if (lastbr > 0 && !this.isStretched(true, elem, panel)) {
          // if aligning...
          const align = this.align(elem, panel); // compute alignment Spot
          ya += align.y * (h - mb.height) + align.offsetY;
          h = mb.height; // only considering Y axis
        }
        const xa = x + (lastbr > 0 ? marg.left : 0);
        this.arrangeElement(elem, xa, ya, mb.width, h);
        x += gw + this.spacing.width;
      }
    } else if (this.direction === 180) {
      let row = 0;
      for (let i = 0; i < elements.length; i++) {
        const elem = elements[i];
        if (!elem.visible) continue;
        const mb = elem.measuredBounds;
        const marg = elem.margin as go.Margin;
        const gw = marg.left + mb.width + marg.right;
        if (x - gw - pad.left < 0.00000005 && i > 0) {
          y += lineBreadths[row++] + this.spacing.height;
          x = xstart;
          if (row === lineLengths.length) row--;
        }
        const lastbr = lineBreadths[row];
        let h = lastbr > 0 ? lastbr - marg.top - marg.bottom : 0;
        let ya = lastbr > 0 ? y + marg.top : y;
        if (lastbr > 0 && !this.isStretched(true, elem, panel)) {
          const align = this.align(elem, panel);
          ya += align.y * (h - mb.height) + align.offsetY;
          h = mb.height;
        }
        const xa = x - gw + (lastbr > 0 ? marg.left : 0);
        this.arrangeElement(elem, xa, ya, mb.width, h);
        x -= gw + this.spacing.width;
      }
    } else if (this.direction === 90) {
      let col = 0;
      for (let i = 0; i < elements.length; i++) {
        const elem = elements[i];
        if (!elem.visible) continue;
        const mb = elem.measuredBounds;
        const marg = elem.margin as go.Margin;
        const gh = marg.top + mb.height + marg.bottom;
        if (y - pad.top > lineLengths[col] - 0.00000005 && i > 0) {
          x += lineBreadths[col++] + this.spacing.width;
          y = ystart;
          if (col === lineLengths.length) col--;
        }
        const lastbr = lineBreadths[col];
        let w = lastbr > 0 ? lastbr - marg.left - marg.right : 0;
        let xa = lastbr > 0 ? x + marg.left : x;
        if (lastbr > 0 && !this.isStretched(false, elem, panel)) {
          const align = this.align(elem, panel);
          xa += align.x * (w - mb.width) + align.offsetX;
          w = mb.width;
        }
        const ya = y + (lastbr > 0 ? marg.top : 0);
        this.arrangeElement(elem, xa, ya, w, mb.height);
        y += gh + this.spacing.height;
      }
    } else if (this.direction === 270) {
      let col = 0;
      for (let i = 0; i < elements.length; i++) {
        const elem = elements[i];
        if (!elem.visible) continue;
        const mb = elem.measuredBounds;
        const marg = elem.margin as go.Margin;
        const gh = marg.top + mb.height + marg.bottom;
        if (y - gh - pad.top < 0.00000005 && i > 0) {
          x += lineBreadths[col++] + this.spacing.width;
          y = ystart - gh;
          if (col === lineLengths.length) col--;
        } else {
          y -= gh;
        }
        const lastbr = lineBreadths[col];
        let w = lastbr > 0 ? lastbr - marg.left - marg.right : 0;
        let xa = lastbr > 0 ? x + marg.left : x;
        if (lastbr > 0 && !this.isStretched(false, elem, panel)) {
          const align = this.align(elem, panel);
          xa += align.x * (w - mb.width) + align.offsetX;
          w = mb.width;
        }
        const ya = y + (lastbr > 0 ? marg.top : 0);
        this.arrangeElement(elem, xa, ya, w, mb.height);
        y -= this.spacing.height;
      }
    }
    (panel as any).panelLayoutState = null; // free up the temporary Arrays
  }
}

go.Panel.definePanelLayout('Flow', new PanelLayoutFlow());