import config
import pypdf
import pdfplumber

class Chars:
   def __init__(self, path, chars, page):
      self.path = path
      self.chars = chars
      self.page = page
      self.n = 0

   def _box(self):
      xs = [i["x0"] for i in self.chars]
      xs += [i["x1"] for i in self.chars]
      ys = [i["y0"] for i in self.chars]
      ys += [i["y1"] for i in self.chars]
      return Box(
         Point(min(xs), min(ys)),
         Point(max(xs), max(ys)),
      )

   def divide_into_columns(self):
      # given median character size
      # drop all above+below first instance
      heights = [i["y1"]-i["y0"] for i in self.chars]
      if not heights:
         return [self]
      median_height = sorted(heights)[len(heights)//2]
      at_least_median_height = [i for i in self.chars if i["y1"]-i["y0"] >= median_height]
      at_least_median_height = sorted(at_least_median_height, key=lambda x:x["y0"])

      # for every sequential pair of chars on same y-coordinate
      # what is median distance?
      distances_when_sequential_and_same_y_coordinate = []
      for i in range(len(self.chars)-1):
         box_0 = Box.from_char(self.chars[i])
         box_1 = Box.from_char(self.chars[i+1])
         if box_0.overlaps_y(box_1):
            delta = box_0.delta_x(box_1)
            distances_when_sequential_and_same_y_coordinate.append(delta)
      median_x_delta_when_same_y = sorted(distances_when_sequential_and_same_y_coordinate)[len(distances_when_sequential_and_same_y_coordinate) // 2]
      median_x_delta_when_same_y = max([5, median_x_delta_when_same_y])

      # merge all naive overlapping boxes
      result = []
      for char in self.chars:
         if result and result[-1]._box().overlaps(Box.from_char(char), clearance=median_x_delta_when_same_y):
            result[-1].merge_in(char)
         else:
            result.append(Chars(self.path, [char], self.page))
      result = [i for i in result if i.n > 2]

      # any clusters shorter than median character and high/lower are header/footer
      result2 = []
      for chars in result:
         chars_box = chars._box()
         are_small = chars_box.y1 - chars_box.y0 < median_height
         are_header = chars_box.y1 < at_least_median_height[0]["y0"]
         are_footer = chars_box.y0 > at_least_median_height[-1]["y1"]
         if not (are_small and (are_header or are_footer)):
            result2.append(chars)
      result = result2

      # merge all vertically overlapping boxes
      changed = True
      while changed:
         changed = False
         result2 = [result[0]]
         for sub in result[1:]:
            found = False
            for sub2 in result2:
               if sub2._box().overlaps_x(sub._box(), clearance=median_x_delta_when_same_y):
                  sub2.merge_in(sub)
                  found = True
                  changed = True
            if not found:
               result2.append(sub)
         result = result2

      j = 0
      for i in result:
         j += 1
         i.merge()
         assert(len(i.chars) == 1)
         #i.chars[0]["x0"] -= median_height
         #i.chars[0]["x1"] += median_height
         #i.chars[0]["y0"] -= median_height
         #i.chars[0]["y1"] += median_height
         bounds = i._box()

         original_reader = pypdf.PdfReader(self.path)
         modified_writer = pypdf.PdfWriter()
         modified_page = original_reader.pages[self.page.page_number-1]
         modified_page.trimbox.upper_right = (bounds.x0, bounds.y0)
         modified_page.trimbox.upper_left  = (bounds.x1, bounds.y0)
         modified_page.trimbox.lower_right = (bounds.x0, bounds.y1)
         modified_page.trimbox.lower_left  = (bounds.x1, bounds.y1)
         modified_page.cropbox.upper_right = (bounds.x0, bounds.y0-median_height)
         modified_page.cropbox.upper_left  = (bounds.x1, bounds.y0-median_height)
         modified_page.cropbox.lower_right = (bounds.x0, bounds.y1+median_height)
         modified_page.cropbox.lower_left  = (bounds.x1, bounds.y1+median_height)
         modified_writer.add_page(modified_page)
         modified_path = "{}/{}-{:03d}-{}.modified.pdf".format(
            config.TEMP_DIR,
            self.path.split("/")[-1],
            self.page.page_number,
            j,
         )
         with open(modified_path, "wb") as mwf:
            modified_writer.write(mwf)
         with pdfplumber.open(modified_path) as modified_pdf:
            i.path = modified_path
            i.page = modified_pdf.pages[0]

      return result

   def merge_in(self, other):
      if isinstance(other, Chars):
         self.chars.extend(other.chars)
      else:
         self.chars.append(other)
      self.merge()

   def merge(self):
      self.n += len(self.chars)-1
      box = self._box()
      self.chars[0]["x0"] = box.corners[0].x
      self.chars[0]["x1"] = box.corners[1].x
      self.chars[0]["y0"] = box.corners[0].y
      self.chars[0]["y1"] = box.corners[1].y
      self.chars = self.chars[:1]

class Box:
   def __init__(self, corner1, corner2):
      self.corners = [corner1, corner2]
      self.diagonal = Line(corner1, corner2)
      self.x0 = min([corner1.x, corner2.x])
      self.x1 = max([corner1.x, corner2.x])
      self.y0 = min([corner1.y, corner2.y])
      self.y1 = max([corner1.y, corner2.y])

   def __str__(self):
      return f'x=[{self.x0},{self.x1}],y=[{self.y0},{self.y1}]'

   def from_char(char):
      return Box(
         Point(char["x0"], char["y0"]),
         Point(char["x1"], char["y1"]),
      )

   def overlaps_x(self, other, clearance=0):
      return self.diagonal.overlaps_x(other.diagonal, clearance=clearance)

   def overlaps_y(self, other, clearance=0):
      return self.diagonal.overlaps_y(other.diagonal, clearance=clearance)

   def overlaps(self, other, clearance=0):
      return self.overlaps_x(other, clearance=clearance) and self.overlaps_y(other, clearance=clearance)

   def delta_x(self, other):
      if self.overlaps_x(other):
         return 0
      return Box.delta(self.x0, self.x1, other.x0, other.x1)

   def delta_y(self, other):
      if self.overlaps_y(other):
         return 0
      return Box.delta(self.y0, self.y1, other.y0, other.y1)

   def delta(a0, a1, b0, b1):
      return min([abs(i) for i in [a0-b0, a0-b1, a1-b0, a1-b1]])

class Line:
   def __init__(self, pointA, pointB):
      self.pointA = pointA
      self.pointB = pointB

   def overlaps_x(self, other, clearance=0):
      mine = self.xs()
      others = other.xs()
      return Line.overlaps(
         mine[0], mine[1],
         others[0], others[1],
         clearance=clearance,
      )

   def overlaps_y(self, other, clearance=0):
      mine = self.ys()
      others = other.ys()
      return Line.overlaps(
         mine[0], mine[1],
         others[0], others[1],
         clearance=clearance,
      )

   def xs(self):
      return sorted([self.pointA.x, self.pointB.x])

   def ys(self):
      return sorted([self.pointA.y, self.pointB.y])

   def overlaps(my_min, my_max, other_min, other_max, clearance=0):
      my_min -= clearance
      my_max += clearance
      other_min -= clearance
      other_max += clearance
      # my.. other..other ..my
      if my_min <= other_min and other_max <= my_max:
         return True
      # other.. my..my ..other
      elif other_min <= my_min and my_max <= other_max:
         return True
      # my..other..my..other
      elif my_min <= other_min and other_min <= my_max and my_max <= other_max:
         return True
      # other..my..other..my
      elif other_min <= my_min and my_min <= other_max and other_max <= my_max:
         return True
      return False

class Point:
   def __init__(self, x, y):
      self.x = x
      self.y = y