Please help me write a phpstr

Existing string: $ str [alignleft] [color # ff00] [font, Tahoma, Helvetica, SimSun, sans-serif] [size5] 2014 Jiuzhaigou Yellow River First Bay, [size] [font] [color] [color # ff00] [font, Tahoma, Helvetica, SimSun, sans-serif]

Existing string: $ str = "[align = left] [color = # ff00] [font =, Tahoma, Helvetica, SimSun, sans-serif] [size = 5] 2014 Jiuzhaigou Yellow River First Bay, [/size] [/font] [/color] [color = # ff00] [font =, Tahoma, helvetica, SimSun, sans-serif]

Existing string:

$ Str = "[align = left] [color = # ff00] [font =, Tahoma, Helvetica, SimSun, sans-serif] [size = 5] 2014 Jiuzhaigou-Yellow River First Bay-, [/size] [/font] [/color] [color = # ff00] [font =, tahoma, Helvetica, SimSun, sans-serif, [attach] 1697 [/attach]
";

The final result is as follows:

$ Str = "2014 Jiuzhaigou-the first bay of the Yellow River-. There are too many things to be sorted back from the two batches. The first batch of photos should be sorted, modified, and sent to the team members ,";

How to compile it? (PHP -- delete all strings in "[]"