1 files changed, 119 insertions, 0 deletions
diff --git a/utils/read_file.py b/utils/read_file.py
new file mode 100644
index 0000000..1906fc7
--- /dev/null
+++ b/utils/read_file.py
@@ -0,0 +1,119 @@
+from datetime import date, datetime
+import re
+import os
+
+
+VALID_DATES_FORMAT = r'\d{4}[-./]\d{1,2}[-./]\d{1,2}'
+VALID_DATES_SEP = '[-./]'
+
+
+class entry:
+    def __init__(self, date: str, comment: str, transactions: list) -> None:
+        self.date = self.__date_from_str(date)
+        self.comment = comment
+        self.transactions = transactions
+
+
+    def __date_from_str(self, date_str: str):
+        """
+        Searches for a valid date on a string and transforms it into ISO
+        format. (YYYY-MM-DD)
+        """
+        my_date = re.findall(VALID_DATES_FORMAT, date_str)[0]
+        year, month, day = re.split(VALID_DATES_SEP, my_date)
+
+        return datetime.fromisoformat(f'{int(year)}-{int(month):02}-{int(day):02}')
+
+    
+    def __str__(self) -> str:
+        result = self.date.strftime('%Y/%m/%d')
+        result += " " + self.comment + "\n"
+
+        for trans in self.transactions:
+            if len(trans) == 2:
+                # TODO: `price` must have a specific format!
+                account, price = trans
+            else:
+                account = trans[0]
+                price = ""
+
+            result += f"    {account:<35} {price:>12}\n"
+
+        return result
+
+
+def give_me_file_contents(path: str):
+    line_comments = ";#%|*"
+    try:
+        with open(path, 'r', encoding='utf8') as fp:
+            result = fp.readlines()
+
+            for line in result:
+                # If line is just empty spaces or empty, ignore it.
+                if len(line.lstrip()) == 0:
+                    continue
+
+                # If first character of line is a line comment, ignore it.
+                first_char = line.lstrip()[0]
+                if first_char in line_comments:
+                    continue
+
+                yield line.strip()
+    
+    except:
+        raise Exception(f"Error while trying to read {path} file.")
+
+
+def is_new_entry(line: str):
+    """
+    Returns `True` if the line contains at least one valid date. This means
+    we're looking at a new transaction.
+    """
+    return re.search(VALID_DATES_FORMAT, line) is not None
+
+
+def read_ledger(path: str):
+    files_to_read = [path]
+    date = None
+    comment = None
+    transactions = None
+
+    results = []
+
+    while files_to_read:
+        current_file = files_to_read.pop()
+
+        for line in give_me_file_contents(current_file):
+            if line.startswith('!include'):
+                file_path = line.split()[-1]
+                base_dir = os.path.dirname(current_file)
+                files_to_read.append(
+                    os.path.join(base_dir, file_path)
+                )
+
+                continue
+
+            if is_new_entry(line) and date is not None:
+                results.append(
+                    entry(date, comment, transactions)
+                )
+
+            if is_new_entry(line):
+                date, comment = line.split(maxsplit=1)
+                transactions = []
+            else:
+                # The line is a new transaction
+                tabs_to_spaces = line.replace('\t', '    ')
+                transactions.append(
+                    re.split(r'\s{2,}', tabs_to_spaces)
+                )
+
+        if date is not None:
+            results.append(
+                entry(date, comment, transactions)
+            )
+            date = None
+            comment = None
+            transactions = None
+
+    return results