1 files changed, 121 insertions, 0 deletions
diff --git a/Scripts/paging.py b/Scripts/paging.py
new file mode 100644
index 0000000..8cde278
--- /dev/null
+++ b/Scripts/paging.py
@@ -0,0 +1,121 @@
+#!/usr/bin/env python3
+
+from math import ceil
+from text_wrapping import TextWrapper
+
+def getSlice(msg: str, idx: int, slice_len: int) -> str:
+    begin = idx * slice_len
+    end = (idx + 1) * slice_len
+    msg_len = len(msg)
+    if msg_len >= end:
+        return msg[begin:end]
+    if msg_len > begin:
+        return msg[begin:end] + (" " * (end - msg_len))
+    return None
+
+def setSlice(msg: str, idx: int, slice_len: int, msg_slice: str) -> str:
+    begin = idx * slice_len
+    end = (idx + 1) * slice_len
+    prefix = msg[0:begin]
+    prefix += " " * (begin - len(prefix))
+    suffix = msg[end:]
+    msg = prefix + msg_slice + suffix
+    return msg
+
+class SingleLinePager:
+    def __init__(self, slice_len: int):
+        self.msg = ""
+        self.slice_len = slice_len
+
+    def reset(self):
+        self.msg = ""
+
+    def getNextSlice(self, msg) -> tuple[str, int]:
+        for i in range(0, ceil(len(msg) / self.slice_len)):
+            old_slice = getSlice(self.msg, i, self.slice_len)
+            new_slice = getSlice(msg, i, self.slice_len)
+            if old_slice != new_slice:
+                self.msg = setSlice(self.msg, i, self.slice_len, new_slice)
+                return new_slice, i
+        return "", -1
+
+class MultiLinePager:
+    def __init__(self, slice_len: int, rows: int, cols: int):
+        # This is a list of lists of SingleLinePagers.
+        # It represents a list of pages, each containing a list of lines.
+        self.pages = []
+        self.slice_len = slice_len
+        self.rows = rows
+        self.cols = cols
+
+    def reset(self):
+        self.pages = []
+
+    def getNextSlice(self, msg) -> tuple[str, int]:
+        pages = TextWrapper(self.rows, self.cols).wrap(msg)
+
+        # Wrapping split the input message along line boundaries and along page
+        # boundaries. However, we're going to treat each page like a single
+        # line, so that `slice_idx` can be used as a region index. Therefore,
+        # we need exactly one SingleLinePager per page.
+        for pi in range(len(self.pages), len(pages)):
+            self.pages.append(SingleLinePager(self.slice_len))
+
+        for pi in range(0, len(pages)):
+            line = "".join(pages[pi])
+            pager = self.pages[pi]
+            msg_slice, slice_idx = pager.getNextSlice(line)
+            if slice_idx != -1:
+                return msg_slice, slice_idx
+        return "", -1
+
+if __name__ == "__main__":
+    assert(getSlice("abcdefghij", 0, 1) == "a")
+    assert(getSlice("abcdefghij", 9, 1) == "j")
+    assert(getSlice("abcdefghij", 0, 2) == "ab")
+    assert(getSlice("abcdefghij", 1, 2) == "cd")
+    assert(getSlice("abcdefghij", 3, 3) == "j  ")
+    assert(getSlice("abcdefghij", 10, 1) == None)
+    assert(getSlice("abcdefghij", 11, 1) == None)
+
+    assert(setSlice("abcdefghij", 1, 2, "kl") == "abklefghij")
+    assert(setSlice("abc", 1, 2, "de") == "abde")
+    assert(setSlice("abc", 0, 2, "de") == "dec")
+
+    slice_len = 2
+    p = SingleLinePager(slice_len)
+    p.msg = "test"
+    assert(p.getNextSlice("test")[0] == "")
+    assert(p.getNextSlice("tast")[0] == "ta")
+    assert(p.getNextSlice("tast")[0] == "")
+
+    p.msg = ""
+    assert(p.getNextSlice("test")[0] == "te")
+    assert(p.msg == "te")
+    assert(p.getNextSlice("test")[0] == "st")
+    assert(p.msg == "test")
+    assert(p.getNextSlice("test")[0] == "")
+    assert(p.msg == "test")
+    assert(p.getNextSlice("tests")[0] == "s ")
+
+    slice_len = 2
+    rows = 2
+    cols = 4
+    p = MultiLinePager(slice_len, rows, cols)
+    assert(p.getNextSlice("")[0] == "")
+    assert(p.getNextSlice("yo")[0] == "yo")
+    assert(p.getNextSlice("yogi")[0] == "gi")
+    assert(p.getNextSlice("yugi")[0] == "yu")
+    assert(p.getNextSlice("yugi is a")[0] == "is")
+    assert(p.getNextSlice("yugi is a")[0] == " a")
+    assert(p.getNextSlice("yugi is a pussy")[0] == "pu")
+    assert(p.getNextSlice("yugi is a pussy")[0] == "s-")
+    assert(p.getNextSlice("yugi is a pussy")[0] == "sy")
+
+    p = MultiLinePager(slice_len, rows, cols)
+    assert(p.getNextSlice("yo")[0] == "yo")
+    assert(p.getNextSlice("yo")[0] == "  ")
+    assert(p.getNextSlice("yo")[0] == "  ")
+    assert(p.getNextSlice("yo")[0] == "  ")
+    assert(p.getNextSlice("yo")[0] == "")
+