//! # quickxml_to_serde
//! Fast and flexible conversion from XML to JSON using [quick-xml](https://github.com/tafia/quick-xml)
//! and [serde](https://github.com/serde-rs/json). Inspired by [node2object](https://github.com/vorot93/node2object).
//!
//! This crate converts XML elements, attributes and text nodes directly into corresponding JSON structures.
//! Some common usage scenarios would be converting XML into JSON for loading into No-SQL databases
//! or sending it to the front end application.
//!
//! Because of the richness and flexibility of XML some conversion behavior is configurable:
//! - attribute name prefixes
//! - naming of text nodes
//! - number format conversion
//!
//! ## Usage example
//! ```
//! extern crate quickxml_to_serde;
//! use quickxml_to_serde::{xml_string_to_json, Config, NullValue};
//!
//! fn main() {
//!    let xml = r#"<a attr1="1"><b><c attr2="001">some text</c></b></a>"#;
//!    let conf = Config::new_with_defaults();
//!    let json = xml_string_to_json(xml.to_owned(), &conf);
//!    println!("{}", json.expect("Malformed XML").to_string());
//!
//!    let conf = Config::new_with_custom_values(true, "", "txt", NullValue::Null);
//!    let json = xml_string_to_json(xml.to_owned(), &conf);
//!    println!("{}", json.expect("Malformed XML").to_string());
//! }
//! ```
//! * **Output with the default config:** `{"a":{"@attr1":1,"b":{"c":{"#text":"some text","@attr2":1}}}}`
//! * **Output with a custom config:** `{"a":{"attr1":1,"b":{"c":{"attr2":"001","txt":"some text"}}}}`
//!
//! ## Additional features
//! Use `quickxml_to_serde = { version = "0.4", features = ["json_types"] }` to enable support for enforcing JSON types     
//! for some XML nodes using xPath-like notations. Example for enforcing attribute `attr2` from the snippet above
//! as JSON String regardless of its contents:
//! ```
//! use quickxml_to_serde::{Config, JsonArray, JsonType};
//!
//! #[cfg(feature = "json_types")]
//! let conf = Config::new_with_defaults()
//!            .add_json_type_override("/a/b/c/@attr2", JsonArray::Infer(JsonType::AlwaysString));
//! ```
//!
//! ## Detailed documentation
//! See [README](https://github.com/AlecTroemel/quickxml_to_serde) in the source repo for more examples, limitations and detailed behavior description.
//!
//! ## Testing your XML files
//!
//! If you want to see how your XML files are converted into JSON, place them into `./test_xml_files` directory
//! and run `cargo test`. They will be converted into JSON and saved in the saved directory.

extern crate minidom;
extern crate serde_json;

use minidom::{Element, Error};
use serde_json::{Map, Number, Value};
#[cfg(feature = "json_types")]
use std::collections::HashMap;
use std::str::FromStr;

#[cfg(test)]
mod tests;

/// Defines how empty elements like `<x />` should be handled.
/// `Ignore` -> exclude from JSON, `Null` -> `"x":null`, EmptyObject -> `"x":{}`.
/// `EmptyObject` is the default option and is how it was handled prior to v.0.4
/// Using `Ignore` on an XML document with an empty root element falls back to `Null` option.
/// E.g. both `<a><x/></a>` and `<a/>` are converted into `{"a":null}`.
#[derive(Debug)]
pub enum NullValue {
    Ignore,
    Null,
    EmptyObject,
}

/// Defines how the values of this Node should be converted into a JSON array with the underlying types.
/// * `Infer` - the nodes are converted into a JSON array only if there are multiple identical elements.
/// E.g. `<a><b>1</b></a>` becomes a map `{"a": {"b": 1 }}` and `<a><b>1</b><b>2</b><b>3</b></a>` becomes
/// an array `{"a": {"b": [1, 2, 3] }}`
/// * `Always` - the nodes are converted into a JSON array regardless of how many there are.
/// E.g. `<a><b>1</b></a>` becomes an array with a single value `{"a": {"b": [1] }}` and  
/// `<a><b>1</b><b>2</b><b>3</b></a>` also becomes an array `{"a": {"b": [1, 2, 3] }}`
#[derive(Debug)]
pub enum JsonArray {
    /// Convert the nodes into a JSON array even if there is only one element
    Always(JsonType),
    /// Convert the nodes into a JSON array only if there are multiple identical elements
    Infer(JsonType),
}

/// Defines which data type to apply in JSON format for consistency of output.
/// E.g., the range of XML values for the same node type may be `1234`, `001234`, `AB1234`.
/// It is impossible to guess with 100% consistency which data type to apply without seeing
/// the entire range of values. Use this enum to tell the converter which data type should
/// be applied.
#[derive(Debug, PartialEq, Clone)]
pub enum JsonType {
    /// Do not try to infer the type and convert the value to JSON string.
    /// E.g. convert `<a>1234</a>` into `{"a":"1234"}` or `<a>true</a>` into `{"a":"true"}`
    AlwaysString,
    /// Convert values included in this member into JSON bool `true` and any other value into `false`.
    /// E.g. `Bool(vec!["True", "true", "TRUE"]) will result in any of these values to become JSON bool `true`.
    Bool(Vec<&'static str>),
    /// Attempt to infer the type by looking at the single value of the node being converted.
    /// Not guaranteed to be consistent across multiple nodes.
    /// E.g. convert `<a>1234</a>` and `<a>001234</a>` into `{"a":1234}`, or `<a>true</a>` into `{"a":true}`
    /// Check if your values comply with JSON data types (case, range, format) to produce the expected result.
    Infer,
}

/// Tells the converter how to perform certain conversions.
/// See docs for individual fields for more info.
#[derive(Debug)]
pub struct Config {
    /// Numeric values starting with 0 will be treated as strings.
    /// E.g. convert `<agent>007</agent>` into `"agent":"007"` or `"agent":7`
    /// Defaults to `false`.
    pub leading_zero_as_string: bool,
    /// Prefix XML attribute names with this value to distinguish them from XML elements.
    /// E.g. set it to `@` for `<x a="Hello!" />` to become `{"x": {"@a":"Hello!"}}`
    /// or set it to a blank string for `{"x": {"a":"Hello!"}}`
    /// Defaults to `@`.
    pub xml_attr_prefix: String,
    /// A property name for XML text nodes.
    /// E.g. set it to `text` for `<x a="Hello!">Goodbye!</x>` to become `{"x": {"@a":"Hello!", "text":"Goodbye!"}}`
    /// XML nodes with text only and no attributes or no child elements are converted into JSON properties with the
    /// name of the element. E.g. <x>Goodbye!</x>` becomes `{"x":"Goodbye!"}`
    /// Defaults to `#text`
    pub xml_text_node_prop_name: String,
    /// Defines how empty elements like `<x />` should be handled.
    pub empty_element_handling: NullValue,
    /// A list of XML paths with their JsonType overrides. They take precedence over the document-wide `json_type`
    /// property. The path syntax is based on xPath: literal element names and attribute names prefixed with `@`.
    /// The path must start with a leading `/`. It is a bit of an inconvenience to remember about it, but it saves
    /// an extra `if`-check in the code to improve the performance.
    /// # Example
    /// - **XML**: `<a><b c="123">007</b></a>`
    /// - path for `c`: `/a/b/@c`
    /// - path for `b` text node (007): `/a/b`
    #[cfg(feature = "json_types")]
    pub json_type_overrides: HashMap<String, JsonArray>,
}

impl Config {
    /// Numbers with leading zero will be treated as numbers.
    /// Prefix XML Attribute names with `@`
    /// Name XML text nodes `#text` for XML Elements with other children
    pub fn new_with_defaults() -> Self {
        Config {
            leading_zero_as_string: false,
            xml_attr_prefix: "@".to_owned(),
            xml_text_node_prop_name: "#text".to_owned(),
            empty_element_handling: NullValue::EmptyObject,
            #[cfg(feature = "json_types")]
            json_type_overrides: HashMap::new(),
        }
    }

    /// Create a Config object with non-default values. See the `Config` struct docs for more info.
    pub fn new_with_custom_values(
        leading_zero_as_string: bool,
        xml_attr_prefix: &str,
        xml_text_node_prop_name: &str,
        empty_element_handling: NullValue,
    ) -> Self {
        Config {
            leading_zero_as_string,
            xml_attr_prefix: xml_attr_prefix.to_owned(),
            xml_text_node_prop_name: xml_text_node_prop_name.to_owned(),
            empty_element_handling,
            #[cfg(feature = "json_types")]
            json_type_overrides: HashMap::new(),
        }
    }

    /// Adds a single JSON Type override rule to the current config.
    /// # Example
    /// - **XML**: `<a><b c="123">007</b></a>`
    /// - path for `c`: `/a/b/@c`
    /// - path for `b` text node (007): `/a/b`
    /// This function will add the leading `/` if it's missing.
    #[cfg(feature = "json_types")]
    pub fn add_json_type_override(self, path: &str, json_type: JsonArray) -> Self {
        let mut conf = self;
        let path = if path.starts_with("/") {
            path.to_owned()
        } else {
            ["/", path].concat()
        };
        conf.json_type_overrides.insert(path, json_type);
        conf
    }
}

impl Default for Config {
    fn default() -> Self {
        Config::new_with_defaults()
    }
}

/// Returns the text as one of `serde::Value` types: int, float, bool or string.
fn parse_text(text: &str, leading_zero_as_string: bool, json_type: &JsonType) -> Value {
    let text = text.trim();

    // enforce JSON String data type regardless of the underlying type
    if json_type == &JsonType::AlwaysString {
        return Value::String(text.into());
    }

    // enforce JSON Bool data type
    #[cfg(feature = "json_types")]
    if let JsonType::Bool(true_values) = json_type {
        if true_values.contains(&text) {
            // any values matching the `true` list are bool/true
            return Value::Bool(true);
        } else {
            // anything else is false
            return Value::Bool(false);
        }
    }

    // ints
    if let Ok(v) = text.parse::<u64>() {
        // don't parse octal numbers and those with leading 0
        // `text` value "0" will always be converted into number 0, "0000" may be converted
        // into 0 or "0000" depending on `leading_zero_as_string`
        if leading_zero_as_string && text.starts_with("0") && (v != 0 || text.len() > 1) {
            return Value::String(text.into());
        }
        return Value::Number(Number::from(v));
    }

    // floats
    if let Ok(v) = text.parse::<f64>() {
        if text.starts_with("0") && !text.starts_with("0.") {
            return Value::String(text.into());
        }
        if let Some(val) = Number::from_f64(v) {
            return Value::Number(val);
        }
    }

    // booleans
    if let Ok(v) = text.parse::<bool>() {
        return Value::Bool(v);
    }

    Value::String(text.into())
}

/// Converts an XML Element into a JSON property
fn convert_node(el: &Element, config: &Config, path: &String) -> Option<Value> {
    // add the current node to the path
    #[cfg(feature = "json_types")]
    let path = [path, "/", el.name()].concat();

    // get the json_type for this node
    let (_, json_type_value) = get_json_type(config, &path);

    // is it an element with text?
    if el.text().trim() != "" {
        // process node's attributes, if present
        if el.attrs().count() > 0 {
            Some(Value::Object(
                el.attrs()
                    .map(|(k, v)| {
                        // add the current node to the path
                        #[cfg(feature = "json_types")]
                        let path = [path.clone(), "/@".to_owned(), k.to_owned()].concat();
                        // get the json_type for this node
                        #[cfg(feature = "json_types")]
                        let (_, json_type_value) = get_json_type(config, &path);
                        (
                            [config.xml_attr_prefix.clone(), k.to_owned()].concat(),
                            parse_text(&v, config.leading_zero_as_string, &json_type_value),
                        )
                    })
                    .chain(vec![(
                        config.xml_text_node_prop_name.clone(),
                        parse_text(
                            &el.text()[..],
                            config.leading_zero_as_string,
                            &json_type_value,
                        ),
                    )])
                    .collect(),
            ))
        } else {
            Some(parse_text(
                &el.text()[..],
                config.leading_zero_as_string,
                &json_type_value,
            ))
        }
    } else {
        // this element has no text, but may have other child nodes
        let mut data = Map::new();

        for (k, v) in el.attrs() {
            // add the current node to the path
            #[cfg(feature = "json_types")]
            let path = [path.clone(), "/@".to_owned(), k.to_owned()].concat();
            // get the json_type for this node
            #[cfg(feature = "json_types")]
            let (_, json_type_value) = get_json_type(config, &path);
            data.insert(
                [config.xml_attr_prefix.clone(), k.to_owned()].concat(),
                parse_text(&v, config.leading_zero_as_string, &json_type_value),
            );
        }

        // process child element recursively
        for child in el.children() {
            match convert_node(child, config, &path) {
                Some(val) => {
                    let name = &child.name().to_string();

                    #[cfg(feature = "json_types")]
                    let path = [path.clone(), "/".to_owned(), name.clone()].concat();
                    let (json_type_array, _) = get_json_type(config, &path);
                    // does it have to be an array?
                    if json_type_array || data.contains_key(name) {
                        // was this property converted to an array earlier?
                        if data.get(name).unwrap_or(&Value::Null).is_array() {
                            // add the new value to an existing array
                            data.get_mut(name)
                                .unwrap()
                                .as_array_mut()
                                .unwrap()
                                .push(val);
                        } else {
                            // convert the property to an array with the existing and the new values
                            let new_val = match data.remove(name) {
                                None => vec![val],
                                Some(temp) => vec![temp, val],
                            };
                            data.insert(name.clone(), Value::Array(new_val));
                        }
                    } else {
                        // this is the first time this property is encountered and it doesn't
                        // have to be an array, so add it as-is
                        data.insert(name.clone(), val);
                    }
                }
                _ => (),
            }
        }

        // return the JSON object if it's not empty
        if !data.is_empty() {
            return Some(Value::Object(data));
        }

        // empty objects are treated according to config rules set by the caller
        match config.empty_element_handling {
            NullValue::Null => Some(Value::Null),
            NullValue::EmptyObject => Some(Value::Object(data)),
            NullValue::Ignore => None,
        }
    }
}

fn xml_to_map(e: &Element, config: &Config) -> Value {
    let mut data = Map::new();
    data.insert(
        e.name().to_string(),
        convert_node(&e, &config, &String::new()).unwrap_or(Value::Null),
    );
    Value::Object(data)
}

/// Converts the given XML string into `serde::Value` using settings from `Config` struct.
pub fn xml_string_to_json(xml: String, config: &Config) -> Result<Value, Error> {
    let root = Element::from_str(xml.as_str())?;
    Ok(xml_to_map(&root, config))
}

/// Returns a tuple for Array and Value enforcements for the current node or
/// `(false, JsonArray::Infer(JsonType::Infer)` if the current path is not found
/// in the list of paths with custom config.
#[cfg(feature = "json_types")]
#[inline]
fn get_json_type(config: &Config, path: &String) -> (bool, JsonType) {
    match config
        .json_type_overrides
        .get(path)
        .unwrap_or(&JsonArray::Infer(JsonType::Infer))
    {
        JsonArray::Infer(v) => (false, v.clone()),
        JsonArray::Always(v) => (true, v.clone()),
    }
}

/// Always returns `(false, JsonArray::Infer(JsonType::Infer)` if `json_types` feature is not enabled.
#[cfg(not(feature = "json_types"))]
#[inline]
fn get_json_type(_config: &Config, _path: &String) -> (bool, JsonType) {
    (false, JsonType::Infer)
}