qubit-redact 0.4.0

// =============================================================================
//    Copyright (c) 2025 - 2026 Haixing Hu.
//
//    SPDX-License-Identifier: Apache-2.0
//
//    Licensed under the Apache License, Version 2.0.
// =============================================================================
//! URI encoding adapter for streaming mask output.

use std::fmt;

use super::BoundedUriWriter;

/// Adapts mask fragments to URI encoding while preserving bounded writes.
pub(crate) struct UriComponentWriter<'a> {
    /// URI output destination.
    rendered: &'a mut BoundedUriWriter,
}

impl UriComponentWriter<'_> {
    /// Creates a writer for one bounded URI component.
    pub(crate) fn new(
        rendered: &mut BoundedUriWriter,
    ) -> UriComponentWriter<'_> {
        UriComponentWriter { rendered }
    }
}

impl fmt::Write for UriComponentWriter<'_> {
    /// Encodes one mask fragment and reports truncation to the mask writer.
    fn write_str(&mut self, value: &str) -> fmt::Result {
        if write_uri_component(value, self.rendered) {
            Ok(())
        } else {
            Err(fmt::Error)
        }
    }
}

/// Writes a replacement while retaining URI-safe delimiters.
fn write_uri_component(value: &str, rendered: &mut BoundedUriWriter) -> bool {
    for byte in value.bytes() {
        if byte.is_ascii_alphanumeric()
            || matches!(
                byte,
                b'-' | b'.'
                    | b'_'
                    | b'~'
                    | b'!'
                    | b'$'
                    | b'\''
                    | b'('
                    | b')'
                    | b'*'
                    | b'+'
                    | b','
                    | b';'
                    | b'='
                    | b':'
            )
        {
            let mut buffer = [0_u8; 4];
            if !rendered.write_str(char::from(byte).encode_utf8(&mut buffer)) {
                return false;
            }
        } else if !rendered.write_percent_encoded(byte) {
            return false;
        }
    }
    true
}