1 files changed, 168 insertions, 0 deletions
diff --git a/src/xpit_/issue.py b/src/xpit_/issue.py
new file mode 100644
index 0000000..53efeef
--- /dev/null
+++ b/src/xpit_/issue.py
@@ -0,0 +1,168 @@
+from __future__ import annotations
+from . import error
+Err = error.Err
+
+class Post:
+    def __init__(self):
+        self.meta: dict[bytes, bytes] = {}
+        self.title: bytes = b""
+        self.replies: list[Post] = []
+
+    def reply_get(self, needle: bytes) -> Post | None:
+        for reply in self.replies:
+            if b"id" not in reply.meta:
+                continue
+            if reply.meta[b"id"] == needle:
+                return reply
+            res = reply.reply_get(needle)
+            if res is not None:
+                return res
+        return None
+
+    def post_count(self) -> int:
+        count = 1
+        for reply in self.replies:
+            count += reply.post_count()
+        return count
+
+def is_newline(c: int) -> bool:
+    return (
+           c == ord('\n')
+        or c == ord('\r')
+    )
+
+def is_whitespace(c: int) -> bool:
+    return (
+           c == ord(' ')
+        or c == ord('\t')
+        or is_newline(c)
+    )
+
+def parse_ini(src: bytes | memoryview, i: int, res: dict[bytes, bytes]) -> int:
+    src = memoryview(src)
+
+    STATE_START = 0
+    STATE_KEY = 1
+    STATE_VALUE = 2
+    state = STATE_START
+
+    key = bytearray()
+    value = bytearray()
+
+    while i < len(src):
+        if state == STATE_START:
+            if src[i:i+4] == b"```\n":
+                return i + 4
+            elif src[i] == ord(' '):
+                pass
+            else:
+                state = STATE_KEY
+                continue
+        elif state == STATE_KEY:
+            if src[i] == ord('='):
+                state = STATE_VALUE
+            else:
+                key.append(src[i])
+        elif state == STATE_VALUE:
+            if is_newline(src[i]) or src[i] == ord(';'):
+                if src[i] == ord(';'):
+                    while len(value) > 0 and is_whitespace(value[-1]):
+                        value.pop()
+                    while i < len(src) and not is_newline(src[i]):
+                        i += 1
+                res[bytes(key)] = bytes(value)
+                state = STATE_START
+                key.clear()
+                value.clear()
+            else:
+                value.append(src[i])
+        else:
+            assert False, "unreachable: state enum not exhausted"
+
+        i += 1
+
+    return -1
+
+def parse(src: bytes | memoryview) -> tuple[Post, Err | None]:
+    def success(post: Post) -> tuple[Post, Err | None]:
+        return post, None
+    def fail(msg: str) -> tuple[Post, Err | None]:
+        return Post(), Err(msg)
+
+    src = memoryview(src)
+    issue = Post()
+    issue_title: bytes | None = None
+    i = 0
+
+    post = issue
+    while i < len(src):
+        if src[i:i+4] == b"\n---":
+            i += 4
+            post = Post()
+            continue
+        if src[i:i+7] == b"```ini\n":
+            i += 7
+            i = parse_ini(src, i, post.meta)
+            if i == -1:
+                return fail("ERR_FAILED_TO_PARSE_INI")
+            if b"reply" in post.meta:
+                reply = issue.reply_get(post.meta[b"reply"])
+                if reply is None:
+                    return fail("ERR_REPLY_TO_NONEXISTENT_ID")
+                reply.replies.append(post)
+            elif post != issue:
+                issue.replies.append(post)
+            continue
+        if issue_title is None and src[i:i+2] == b"# ":
+            i += 2
+            title_start = i
+            while i < len(src):
+                if is_newline(src[i]):
+                    break
+                i += 1
+            issue_title = bytes(src[title_start:i])
+            continue
+
+        i += 1
+
+    if issue_title is None:
+        return fail("ERR_ISSUE_NO_TITLE")
+    issue.title = issue_title
+
+    return success(issue)
+
+def clean_after_edit(src: bytes | memoryview, last_ini_prefix: bytes) -> bytes:
+    src = memoryview(src)
+    last_ini_prefix = bytes(last_ini_prefix)
+    res: list[int] = []
+    i = 0
+    last_ini_start = 0
+    while i < len(src):
+        while i < len(src):
+            if src[i:i+7] == b"```ini\n":
+                res.extend(src[i:i+7])
+                last_ini_start = len(res)
+                i += 7
+                break
+            res.append(src[i])
+            i += 1
+
+        while i < len(src):
+            # inside ini
+            if src[i:i+4] == b"\n```":
+                res.extend(src[i:i+4])
+                i += 4
+                break
+            elif src[i:i+3] == b" ; ":
+                i += 3
+                while i < len(src):
+                    if is_newline(src[i]):
+                        break
+                    i += 1
+            res.append(src[i])
+            i += 1
+
+    res[last_ini_start:last_ini_start] = last_ini_prefix
+
+    return bytes(res)
+