Validate Input Against Policies

MediumPython

Problem

Intercom Inbox receives user-submitted text that must satisfy configurable security policies before processing. Implement a validator that checks an ASCII string against an ordered list of policies and returns the names of every policy it violates.

Formal Specification

Implement validate_input(text, policies), where text is a string and policies is a list of dictionaries. Each dictionary contains a unique name, a type, and, when required, a value:

min_length: value is the minimum number of characters.
max_length: value is the maximum number of characters.
must_include: value is one of lowercase, uppercase, digit, or special.
forbid_substring: value is a case-insensitive substring that must not occur.
max_consecutive: value is the maximum number of identical consecutive characters.

Return a list of policy names violated by text, preserving the order of policies. Return an empty list when all policies pass.

Constraints

1 <= len(text) <= 100000
1 <= len(policies) <= 1000
The input contains printable ASCII characters
Policy names are unique
Every policy has a valid type and value

Function Signature

def validate_input(text, policies):

Formal Specification

Implement validate_input(text, policies), where text is a string and policies is a list of dictionaries. Each dictionary contains a unique name, a type, and, when required, a value:

min_length: value is the minimum number of characters.
max_length: value is the maximum number of characters.
must_include: value is one of lowercase, uppercase, digit, or special.
forbid_substring: value is a case-insensitive substring that must not occur.
max_consecutive: value is the maximum number of identical consecutive characters.

Return a list of policy names violated by text, preserving the order of policies. Return an empty list when all policies pass.