package main

import "testing"

// TestAxisMap checks centering when content fits and clamped scrolling when it
// does not.
func TestAxisMap(t *testing.T) {
	cases := []struct {
		name                  string
		pane, content, focus  int
		wantBlank, wantScroll int
	}{
		{"fits centered", 100, 40, 0, 30, 0},
		{"exact fit", 40, 40, 0, 0, 0},
		{"scroll centered on focus", 40, 100, 50, 0, 30},
		{"scroll clamped low", 40, 100, 0, 0, 0},
		{"scroll clamped high", 40, 100, 999, 0, 60},
	}
	for _, c := range cases {
		blank, scroll := axisMap(c.pane, c.content, c.focus)
		if blank != c.wantBlank || scroll != c.wantScroll {
			t.Errorf("%s: axisMap(%d,%d,%d) = (%d,%d), want (%d,%d)",
				c.name, c.pane, c.content, c.focus, blank, scroll, c.wantBlank, c.wantScroll)
		}
	}
}

// TestPtToCell checks the point->cell mapping and that moving a point by one
// stepPt lands exactly one cell away (the property the cursor/stamp nudges
// rely on).
func TestPtToCell(t *testing.T) {
	// Page 600x800 pt rendered to a 120x80 px image (scaleX=0.2, scaleY=0.1),
	// fitting within the pane (no scroll), centered with a 4-cell/2-px margin.
	v := &view{
		cols: 128, rows: 41,
		scaleX: 0.2, scaleY: 0.1,
		blankX: 4, blankY: 2,
		scrollX: 0, scrollY: 0,
		pageH: 800,
	}

	// Bottom-left of the page maps to the bottom-left of the image area.
	col, row := v.ptToCell(0, 0)
	if col != 4 || row != 41 {
		t.Errorf("ptToCell(0,0) = (%d,%d), want (4,41)", col, row)
	}

	// One horizontal step moves exactly one column; one vertical step one row.
	sx, sy := v.stepPt()
	x, y := 300.0, 400.0
	c0, r0 := v.ptToCell(x, y)
	c1, _ := v.ptToCell(x+sx, y)
	if c1-c0 != 1 {
		t.Errorf("one stepPt in x moved %d cols, want 1", c1-c0)
	}
	_, r1 := v.ptToCell(x, y+sy)
	if r0-r1 != 1 { // +y is up, which is a smaller row number
		t.Errorf("one stepPt in y moved %d rows, want 1", r0-r1)
	}
}