geolite 0.0.17

open source geocode solution
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use super::entity::admin_level;

enum template_segment {
  literal(String),
  placeholder(u8),
  house_number,
}

fn parse_template(format: &str) -> Result<Vec<template_segment>, String> {
  let mut segments: Vec<template_segment> = Vec::new();
  let mut buf = String::new();
  let bytes = format.as_bytes();
  let mut i = 0;
  while i < bytes.len() {
    if bytes[i] == b'{' {
      let Some(rel_close) = format[i..].find('}') else {
        return Err(
          "friendly_name_format: unterminated placeholder (missing closing '}')".to_string(),
        );
      };
      let inner = &format[i + 1..i + rel_close];
      let segment = if inner == "house_number" {
        template_segment::house_number
      } else {
        match inner
          .strip_prefix("admin_level_")
          .and_then(|s| s.strip_suffix("_name"))
        {
          Some(mid) => template_segment::placeholder(mid.parse::<u8>().map_err(|_| {
            format!("friendly_name_format: invalid admin level '{mid}' (expected an integer 0-255)")
          })?),
          None => {
            return Err(format!(
              "friendly_name_format: unknown field '{inner}' (expected 'admin_level_<N>_name' or 'house_number')"
            ));
          }
        }
      };
      if !buf.is_empty() {
        segments.push(template_segment::literal(std::mem::take(&mut buf)));
      }
      segments.push(segment);
      i += rel_close + 1;
      continue;
    }
    let ch = format[i..].chars().next().unwrap();
    buf.push(ch);
    i += ch.len_utf8();
  }
  if !buf.is_empty() {
    segments.push(template_segment::literal(buf));
  }
  Ok(segments)
}

pub fn validate_friendly_name_format(s: &str) -> Result<String, String> {
  parse_template(s)?;
  Ok(s.to_string())
}

pub(super) fn render_friendly_name(
  format: &str,
  admin_levels: &[admin_level],
  house_number: Option<&str>,
) -> String {
  let segments = parse_template(format)
    .expect("friendly_name_format must be validated at the parse boundary before render");
  let mut out = String::new();
  let mut skip_next_literal = false;
  for seg in segments {
    let value = match seg {
      template_segment::literal(s) => {
        if skip_next_literal {
          skip_next_literal = false;
        } else {
          out.push_str(&s);
        }
        continue;
      }
      template_segment::placeholder(level) => admin_levels
        .iter()
        .find(|a| a.level == level)
        .map(|a| a.name.as_str()),
      template_segment::house_number => house_number,
    };
    match value {
      Some(name) => {
        out.push_str(name);
        skip_next_literal = false;
      }
      None => skip_next_literal = true,
    }
  }
  out
    .trim_matches(|c: char| c == ',' || c.is_whitespace())
    .to_string()
}

pub(super) fn place_label<'a>(
  own: (&'a str, Option<&'a str>),
  house_number: Option<&'a str>,
  ancestors: impl Iterator<Item = (&'a str, Option<&'a str>)>,
) -> String {
  let mut names: Vec<&str> = vec![own.0];
  names.extend(house_number);
  let mut post_codes: Vec<Option<&str>> = vec![own.1];
  for (name, post_code) in ancestors {
    names.push(name);
    post_codes.push(post_code);
  }
  let mut label = names.join(", ");
  for post_code in post_codes.iter().rev() {
    if let Some(pc) = post_code.map(str::trim).filter(|s| !s.is_empty()) {
      label.push_str(", ");
      label.push_str(pc);
    }
  }
  label
}