src/database/reader.py

@@ -0,0 +1,127 @@
+import sqlite3
+import typing
+import re
+
+
+
+SEARCH_PARAMS = {
+    'timestamp': int,
+    'is_hidden': bool,  # boolean
+    'comment_id': str,  # strings
+    'parent_id': str,
+    'channel_name': str,
+    'channel_url': str,
+    'channel_id': str,
+    'claim_id': str,
+    'signature': str,
+    'signing_ts': str,
+    'comment': str,
+}
+
+TABLE = 'COMMENTS_ON_CLAIMS'
+
+
+ID_PARAM_LENS = {
+    'comment_id': 64,
+    'channel_id': 40,
+    'claim_id': 40,
+    'signature': 128,
+    'parent_id': 64
+}
+
+IDENTIFIERS = {
+    'signature',
+    'comment_id',
+    'parent_id',
+    'channel_id',
+    'claim_id'
+}
+
+GROUPABLE = {
+    'channel_name',
+    'channel_url'
+} | IDENTIFIERS
+
+GROUP_PARAMS = re.compile(rf"({'|'.join(GROUPABLE)})s")
+ID_PARAMS = re.compile(rf"({'|'.join(IDENTIFIERS)})")
+
+
+OPS = {
+    'eq': '=',
+    'gt': '>',
+    'lt': '<',
+    'gte': '>=',
+    'lte': '<=',
+    'like': 'LIKE',
+    'is': 'IS',
+    'is_not': 'IS NOT',
+    'is_null': 'IS NULL',
+    'is_not_null': 'IS NOT NULL',
+    'in': 'IN',
+    'not_in': 'NOT IN'
+}
+
+
+def create_query(cols=None, **constraints):
+    table = 'COMMENTS_ON_CLAIMS'
+
+    ops = {'>': '__gt', '>=': '__gte', '<': '__lt', '<=': '__lte'}
+    if 'timestamp' in constraints:
+        time = constraints.pop('timestamp')
+        prefix = f'{table}.timestamp'
+        if isinstance(time, str):
+            if len(time) > 2 and time[:2] in ops:
+                constraints[f'{prefix}{ops[time[:2]]}'] = int(time[2:])
+            elif len(time) > 1 and time[:1] in ops:
+                constraints[f'{prefix}{ops[time[:1]]}'] = int(time[1:])
+            else:
+                constraints[f'{prefix}__eq'] = int(time)
+        elif isinstance(time, int):
+            constraints[f'{prefix}__eq'] = time
+
+    sql = ['SELECT']
+    if isinstance(cols, (list, tuple)):
+        sql.append(', '.join(cols))
+    elif isinstance(cols, dict):
+        sql.append(', '.join(f'{col} AS {cola}' for col, cola in cols.items()))
+    else:
+        sql.append('*')
+    sql += ['FROM', table]
+    if len(constraints) > 0:
+        conditions, constraints = constraints_to_sql(**constraints)
+        sql += ['WHERE', conditions]
+
+    return '\n'.join(sql), constraints
+
+
+def constraints_to_sql(**constraints):
+    sql_params = {}
+    sql_stmts = []
+    for constraint, value in constraints.items():
+        if constraint.find('__'):
+            col, op = constraint.split('__')
+            param = col.split('.')[1]
+            statement = [param, OPS[op]]
+            if op[-2:] == 'in' and isinstance(value, (list, tuple, set)):
+                param_list = ", ".join(f':{param}{i}' for i in range(len(value)))
+                statement.append(f'({param_list})')
+                sql_params.update({f'{param}{i}': v for i, v in enumerate(value)})
+            elif 'null' not in op:
+                statement.append(':' + param)
+                sql_params[param] = value
+            sql_stmts.append(' '.join(statement))
+
+    inner_where = ' AND '.join(sql_stmts)
+    return inner_where, sql_params
+
+
+def _page_to_limit(**constraints):
+    limit = constraints.pop('page_size', None)
+    page = constraints.pop('page', None)
+    if limit and isinstance(int, limit):
+        constraints['LIMIT'] = limit
+        if page and isinstance(page, int):
+            constraints['OFFSET'] = limit * (page - 1)
+    return constraints
+
+