Refactor application and runtime boundaries

src/a2ui/evaluation.rs

@@ -0,0 +1,451 @@
+use super::*;
+
+pub(super) fn resolve(value: &Value, data: &Value) -> Result<Value, String> {
+    resolve_at(value, data, data)
+}
+
+pub(super) fn resolve_at(value: &Value, data: &Value, context: &Value) -> Result<Value, String> {
+    if let Some(path) = value
+        .as_object()
+        .and_then(|value| value.get("path"))
+        .and_then(Value::as_str)
+    {
+        let source = if path.starts_with('/') { data } else { context };
+        let pointer = if path.starts_with('/') {
+            normalize_pointer(path).to_owned()
+        } else {
+            format!("/{path}")
+        };
+        return Ok(source.pointer(&pointer).cloned().unwrap_or(Value::Null));
+    }
+    if let Some(call) = value
+        .as_object()
+        .and_then(|value| value.get("call"))
+        .and_then(Value::as_str)
+    {
+        return evaluate(
+            call,
+            value.get("args").unwrap_or(&Value::Null),
+            data,
+            context,
+        );
+    }
+    match value {
+        Value::Array(values) => values
+            .iter()
+            .map(|value| resolve_at(value, data, context))
+            .collect::<Result<Vec<_>, _>>()
+            .map(Value::Array),
+        Value::Object(values) => values
+            .iter()
+            .map(|(key, value)| Ok((key.clone(), resolve_at(value, data, context)?)))
+            .collect::<Result<Map<_, _>, String>>()
+            .map(Value::Object),
+        _ => Ok(value.clone()),
+    }
+}
+
+pub(super) fn evaluate(
+    call: &str,
+    args: &Value,
+    data: &Value,
+    context: &Value,
+) -> Result<Value, String> {
+    if !FUNCTIONS.contains(&call) {
+        return Err(format!("function `{call}` is not declared by the catalog"));
+    }
+    let args = args
+        .as_object()
+        .ok_or_else(|| format!("function `{call}` requires object args"))?;
+    let value = || resolve_at(args.get("value").unwrap_or(&Value::Null), data, context);
+    match call {
+        "required" => Ok(Value::Bool(match value()? {
+            Value::Null => false,
+            Value::String(value) => !value.is_empty(),
+            Value::Array(value) => !value.is_empty(),
+            Value::Object(value) => !value.is_empty(),
+            _ => true,
+        })),
+        "regex" => {
+            let pattern = args
+                .get("pattern")
+                .and_then(Value::as_str)
+                .ok_or_else(|| "regex requires a pattern".to_owned())?;
+            let regex = Regex::new(pattern).map_err(|error| format!("invalid regex: {error}"))?;
+            Ok(Value::Bool(regex.is_match(&display_value(&value()?))))
+        }
+        "length" => {
+            let length = display_value(&value()?).chars().count() as u64;
+            let min = args.get("min").and_then(Value::as_u64).unwrap_or(0);
+            let max = args.get("max").and_then(Value::as_u64).unwrap_or(u64::MAX);
+            Ok(Value::Bool((min..=max).contains(&length)))
+        }
+        "numeric" => {
+            let resolved = value()?;
+            let number = resolved
+                .as_f64()
+                .or_else(|| resolved.as_str().and_then(|value| value.parse().ok()));
+            let min = args
+                .get("min")
+                .and_then(Value::as_f64)
+                .unwrap_or(f64::NEG_INFINITY);
+            let max = args
+                .get("max")
+                .and_then(Value::as_f64)
+                .unwrap_or(f64::INFINITY);
+            Ok(Value::Bool(
+                number.is_some_and(|number| (min..=max).contains(&number)),
+            ))
+        }
+        "email" => {
+            let email = display_value(&value()?);
+            let valid = Regex::new(r"^[^\s@]+@[^\s@]+\.[^\s@]+$")
+                .unwrap()
+                .is_match(&email);
+            Ok(Value::Bool(valid))
+        }
+        "formatString" => Ok(Value::String(interpolate(
+            &display_value(&value()?),
+            data,
+            context,
+        )?)),
+        "formatNumber" => {
+            let number = value()?.as_f64().unwrap_or(0.0);
+            let digits = resolve_at(args.get("decimals").unwrap_or(&json!(2)), data, context)?
+                .as_f64()
+                .map(|value| value.max(0.0) as u64)
+                .unwrap_or(2)
+                .min(12) as usize;
+            let formatted = format!("{number:.digits$}");
+            Ok(Value::String(
+                if resolve_at(
+                    args.get("grouping").unwrap_or(&Value::Bool(true)),
+                    data,
+                    context,
+                )?
+                .as_bool()
+                .unwrap_or(true)
+                {
+                    group_number(&formatted)
+                } else {
+                    formatted
+                },
+            ))
+        }
+        "formatCurrency" => {
+            let number = value()?.as_f64().unwrap_or(0.0);
+            let currency = display_value(&resolve_at(
+                args.get("currency").unwrap_or(&Value::Null),
+                data,
+                context,
+            )?);
+            let digits = resolve_at(args.get("decimals").unwrap_or(&json!(2)), data, context)?
+                .as_f64()
+                .map(|value| value.max(0.0) as u64)
+                .unwrap_or(2)
+                .min(12) as usize;
+            let formatted = format!("{number:.digits$}");
+            let number = if resolve_at(
+                args.get("grouping").unwrap_or(&Value::Bool(true)),
+                data,
+                context,
+            )?
+            .as_bool()
+            .unwrap_or(true)
+            {
+                group_number(&formatted)
+            } else {
+                formatted
+            };
+            Ok(Value::String(format!("{currency} {number}")))
+        }
+        "formatDate" => {
+            let input = display_value(&value()?);
+            let date =
+                time::OffsetDateTime::parse(&input, &time::format_description::well_known::Rfc3339)
+                    .map_err(|error| format!("formatDate requires an RFC 3339 value: {error}"))?;
+            let pattern = display_value(&resolve_at(
+                args.get("format").unwrap_or(&Value::Null),
+                data,
+                context,
+            )?);
+            Ok(Value::String(format_date(date, &pattern)))
+        }
+        "pluralize" => {
+            let number = value()?.as_f64().unwrap_or(0.0);
+            let key = if number == 0.0 && args.contains_key("zero") {
+                "zero"
+            } else if number == 1.0 && args.contains_key("one") {
+                "one"
+            } else if number == 2.0 && args.contains_key("two") {
+                "two"
+            } else {
+                "other"
+            };
+            resolve_at(args.get(key).unwrap_or(&Value::Null), data, context)
+        }
+        "and" | "or" => {
+            let values = args
+                .get("values")
+                .and_then(Value::as_array)
+                .ok_or_else(|| format!("{call} requires array `values`"))?;
+            let values = values
+                .iter()
+                .map(|value| {
+                    resolve_at(value, data, context)?
+                        .as_bool()
+                        .ok_or_else(|| format!("{call} requires boolean values"))
+                })
+                .collect::<Result<Vec<_>, _>>()?;
+            Ok(Value::Bool(if call == "and" {
+                values.into_iter().all(|value| value)
+            } else {
+                values.into_iter().any(|value| value)
+            }))
+        }
+        "not" => {
+            Ok(Value::Bool(!value()?.as_bool().ok_or_else(|| {
+                "not requires a boolean value".to_owned()
+            })?))
+        }
+        "openUrl" => Ok(Value::Null),
+        "@index" => {
+            let index = TEMPLATE_INDEX
+                .with(Cell::get)
+                .ok_or_else(|| "@index is only available in a list template".to_owned())?;
+            let offset = args
+                .get("offset")
+                .map(|value| resolve_at(value, data, context))
+                .transpose()?
+                .and_then(|value| value.as_i64())
+                .unwrap_or(0);
+            Ok(json!(index as i64 + offset))
+        }
+        _ => unreachable!(),
+    }
+}
+
+fn interpolate(template: &str, data: &Value, context: &Value) -> Result<String, String> {
+    let mut output = String::new();
+    let mut offset = 0;
+    while let Some(relative) = template[offset..].find("${") {
+        let start = offset + relative;
+        if start > offset && template.as_bytes()[start - 1] == b'\\' {
+            output.push_str(&template[offset..start - 1]);
+            output.push_str("${");
+            offset = start + 2;
+            continue;
+        }
+        output.push_str(&template[offset..start]);
+        let end = expression_end(template, start + 2)
+            .ok_or_else(|| "formatString contains an unclosed expression".to_owned())?;
+        output.push_str(&display_value(&evaluate_expression(
+            &template[start + 2..end],
+            data,
+            context,
+        )?));
+        offset = end + 1;
+    }
+    output.push_str(&template[offset..]);
+    Ok(output)
+}
+
+fn expression_end(text: &str, mut offset: usize) -> Option<usize> {
+    let mut depth = 1;
+    let mut quote = None;
+    while offset < text.len() {
+        let character = text[offset..].chars().next()?;
+        if let Some(current) = quote {
+            if character == current && text.as_bytes().get(offset.wrapping_sub(1)) != Some(&b'\\') {
+                quote = None;
+            }
+        } else if matches!(character, '\'' | '"') {
+            quote = Some(character);
+        } else if text[offset..].starts_with("${") {
+            depth += 1;
+            offset += 2;
+            continue;
+        } else if character == '}' {
+            depth -= 1;
+            if depth == 0 {
+                return Some(offset);
+            }
+        }
+        offset += character.len_utf8();
+    }
+    None
+}
+
+fn evaluate_expression(expression: &str, data: &Value, context: &Value) -> Result<Value, String> {
+    let expression = expression.trim();
+    if let Some(open) = expression.find('(')
+        && expression.ends_with(')')
+    {
+        let call = expression[..open].trim();
+        let mut args = Map::new();
+        for argument in split_expression_args(&expression[open + 1..expression.len() - 1]) {
+            let colon = top_level_separator(argument, ':')
+                .ok_or_else(|| format!("formatString argument `{argument}` must be named"))?;
+            let name = argument[..colon].trim();
+            if name.is_empty() {
+                return Err("formatString contains an empty argument name".into());
+            }
+            args.insert(
+                name.to_owned(),
+                expression_value(argument[colon + 1..].trim(), data, context)?,
+            );
+        }
+        return evaluate(call, &Value::Object(args), data, context);
+    }
+    let (source, pointer) = if expression.starts_with('/') {
+        (data, normalize_pointer(expression).to_owned())
+    } else {
+        (context, format!("/{expression}"))
+    };
+    Ok(source.pointer(&pointer).cloned().unwrap_or(Value::Null))
+}
+
+fn split_expression_args(input: &str) -> Vec<&str> {
+    let mut arguments = Vec::new();
+    let mut start = 0;
+    while let Some(relative) = top_level_separator(&input[start..], ',') {
+        arguments.push(input[start..start + relative].trim());
+        start += relative + 1;
+    }
+    if !input[start..].trim().is_empty() {
+        arguments.push(input[start..].trim());
+    }
+    arguments
+}
+
+fn top_level_separator(input: &str, separator: char) -> Option<usize> {
+    let mut round = 0;
+    let mut braces = 0;
+    let mut quote = None;
+    for (index, character) in input.char_indices() {
+        if let Some(current) = quote {
+            if character == current && input.as_bytes().get(index.wrapping_sub(1)) != Some(&b'\\') {
+                quote = None;
+            }
+            continue;
+        }
+        match character {
+            '\'' | '"' => quote = Some(character),
+            '(' => round += 1,
+            ')' => round -= 1,
+            '{' => braces += 1,
+            '}' => braces -= 1,
+            _ if character == separator && round == 0 && braces == 0 => return Some(index),
+            _ => {}
+        }
+    }
+    None
+}
+
+fn expression_value(expression: &str, data: &Value, context: &Value) -> Result<Value, String> {
+    if expression.starts_with("${") && expression.ends_with('}') {
+        return evaluate_expression(&expression[2..expression.len() - 1], data, context);
+    }
+    if expression.starts_with('\'') && expression.ends_with('\'') && expression.len() >= 2 {
+        return Ok(Value::String(
+            expression[1..expression.len() - 1].to_owned(),
+        ));
+    }
+    if let Ok(value) = serde_json::from_str(expression) {
+        return Ok(value);
+    }
+    if expression.starts_with('/') {
+        return Ok(data
+            .pointer(normalize_pointer(expression))
+            .cloned()
+            .unwrap_or(Value::Null));
+    }
+    Ok(Value::String(expression.to_owned()))
+}
+
+fn group_number(number: &str) -> String {
+    let (whole, fraction) = number.split_once('.').unwrap_or((number, ""));
+    let (sign, digits) = whole
+        .strip_prefix('-')
+        .map_or(("", whole), |digits| ("-", digits));
+    let mut grouped = String::with_capacity(number.len() + number.len() / 3);
+    grouped.push_str(sign);
+    for (index, digit) in digits.chars().enumerate() {
+        if index > 0 && (digits.len() - index).is_multiple_of(3) {
+            grouped.push(',');
+        }
+        grouped.push(digit);
+    }
+    if !fraction.is_empty() {
+        grouped.push('.');
+        grouped.push_str(fraction);
+    }
+    grouped
+}
+
+pub(super) fn format_date(date: time::OffsetDateTime, pattern: &str) -> String {
+    const MONTHS: [&str; 12] = [
+        "January",
+        "February",
+        "March",
+        "April",
+        "May",
+        "June",
+        "July",
+        "August",
+        "September",
+        "October",
+        "November",
+        "December",
+    ];
+    const DAYS: [&str; 7] = [
+        "Monday",
+        "Tuesday",
+        "Wednesday",
+        "Thursday",
+        "Friday",
+        "Saturday",
+        "Sunday",
+    ];
+    let month = MONTHS[date.month() as usize - 1];
+    let day = DAYS[date.weekday().number_days_from_monday() as usize];
+    let hour_12 = match date.hour() % 12 {
+        0 => 12,
+        hour => hour,
+    };
+    let replacements = [
+        ("EEEE", day.to_owned()),
+        ("MMMM", month.to_owned()),
+        ("yyyy", format!("{:04}", date.year())),
+        ("MMM", month[..3].to_owned()),
+        ("yy", format!("{:02}", date.year().rem_euclid(100))),
+        ("MM", format!("{:02}", date.month() as u8)),
+        ("dd", format!("{:02}", date.day())),
+        ("HH", format!("{:02}", date.hour())),
+        ("hh", format!("{hour_12:02}")),
+        ("mm", format!("{:02}", date.minute())),
+        ("ss", format!("{:02}", date.second())),
+        ("E", day[..3].to_owned()),
+        ("M", (date.month() as u8).to_string()),
+        ("d", date.day().to_string()),
+        ("H", date.hour().to_string()),
+        ("h", hour_12.to_string()),
+        ("a", if date.hour() < 12 { "AM" } else { "PM" }.to_owned()),
+    ];
+    let mut output = String::new();
+    let mut remaining = pattern;
+    while !remaining.is_empty() {
+        if let Some((token, replacement)) = replacements
+            .iter()
+            .find(|(token, _)| remaining.starts_with(token))
+        {
+            output.push_str(replacement);
+            remaining = &remaining[token.len()..];
+        } else {
+            let character = remaining.chars().next().unwrap();
+            output.push(character);
+            remaining = &remaining[character.len_utf8()..];
+        }
+    }
+    output
+}