4 jewels in a row. 7x7 Lines

Lines 7x7 is a game play on 7x7 board with balls of eight different colors.
The goal is to connect 4 or more balls of the same color to a horizontal, vertical or diagonal line.
The player can move one ball per turn, and the player may only move a ball to a particular place if there is a path
(linked set of vertical and horizontal empty cells) between the current position of the ball and the desired destination.
If the player does form such lines of at least four balls of the same color, the balls in those lines disappear,
and he gains one turn, i.e. he can move another ball.
If not, three new balls are added, and the game continues until the board is full.

Good brain trainer!