mavinspect 0.1.0-alpha2

use std::collections::HashMap;
use std::io::{BufRead, Read};

use quick_xml::events::{BytesStart, BytesText, Event};
use quick_xml::reader::Reader;

use crate::parser::errors::XmlParseError;
use crate::protocol::{Enum, Message, MessageId};

use super::context::XmlParsingContext;
use super::context_stack::XmlParsingContextStack;
use super::entities::deprecated::XmlDeprecated;
use super::entities::enums::{
    XmlEnum, XmlEnumEntry, XmlEnumEntryMavCmdFlags, XmlEnumEntryMavCmdParam,
};
use super::entities::messages::{XmlMessage, XmlMessageField};

#[derive(Debug)]
pub struct XmlParser<'a> {
    dialect_name: Option<&'a str>,
    enums: &'a mut HashMap<String, Enum>,
    messages: &'a mut HashMap<MessageId, Message>,
    includes: Vec<String>,
    version: Option<u8>, // TODO: change to `u32`
    dialect_id: Option<u32>,
    context_stack: XmlParsingContextStack,
    tag_stack: Vec<String>,
}

impl<'a> XmlParser<'a> {
    /// Default constructor
    ///
    /// Receives borrows mutable references to maps of [`Enum`]'s and [`Message`]'s which will be
    /// updated during parsing in [`Self::parse`].
    ///
    /// # Arguments
    ///
    /// * `enums` - mutable reference to a map of [`Enum`]'s which will be updated during the
    ///   parsing in [`Self::parse`].
    /// * `messages` - mutable reference to a map of [`Message`]'s which will be updated during the
    ///   parsing in [`Self::parse`].
    pub fn new(
        enums: &'a mut HashMap<String, Enum>,
        messages: &'a mut HashMap<MessageId, Message>,
    ) -> Self {
        Self {
            dialect_name: None,
            enums,
            messages,
            includes: vec![],
            version: None,
            dialect_id: None,
            context_stack: XmlParsingContextStack::new(),
            tag_stack: Vec::new(),
        }
    }

    /// Last parsed dialect name.
    pub fn dialect_name(&self) -> &Option<&str> {
        &self.dialect_name
    }

    /// Last parsed dialect includes.
    pub fn includes(&self) -> &Vec<String> {
        &self.includes
    }

    /// Last parsed dialect version.
    pub fn version(&self) -> &Option<u8> {
        &self.version
    }

    /// Last parsed dialect ID.
    pub fn dialect_id(&self) -> &Option<u32> {
        &self.dialect_id
    }

    /// Parses messages and enums from MAVLink XML message definitions.
    ///
    /// See [MAVLink XML schema](https://mavlink.io/en/guide/xml_schema.html) for details.
    ///
    /// # Arguments
    ///
    /// * `dialect_name` - name of the dialect to parse.
    /// * `reader` - reader for XML data (this could be a file or string reader).
    pub fn parse<T: BufRead + Read>(
        &mut self,
        dialect_name: &'a str,
        reader: &mut Reader<T>,
    ) -> Result<(), XmlParseError> {
        // Clear parser state
        self.clear();
        // Set current dialect name
        self.dialect_name = Some(dialect_name);

        // Allocate buffer
        let mut buf = Vec::new();

        // Parse XML message definition
        loop {
            match reader.read_event_into(&mut buf) {
                Err(e) => panic!("Error at position {}: {:?}", reader.buffer_position(), e),
                // exits the loop when reaching end of file
                Ok(Event::Eof) => break,
                // Process tag start
                Ok(Event::Start(e)) => {
                    let tag_name = String::from_utf8_lossy(e.name().as_ref()).to_string();
                    self.push_tag(tag_name.as_ref())?;

                    match self.tag_stack.last().unwrap().as_str() {
                        // MavLink
                        "mavlink" => self.process_mavlink_start()?,
                        // Include
                        "include" => self.process_include_start()?,
                        // Version
                        "version" => self.process_version_start()?,
                        // Dialect
                        "dialect" => self.process_dialect_start()?,

                        // Enum
                        "enum" => self.process_enum_start(e)?,
                        // Enum entry
                        "entry" => self.process_enum_entry_start(e)?,
                        // Enum entry param
                        "param" => self.process_enum_entry_mav_cmd_param_start(e)?,

                        // Message
                        "message" => self.process_message_start(e)?,
                        // Message field
                        "field" => self.process_message_field_start(e)?,

                        // Description
                        "description" => self.process_description_start()?,
                        // Deprecation status
                        "deprecated" => self.process_deprecated_start(e)?,
                        // Message is work in progress
                        "wip" => self.process_wip_start()?,
                        // Message extensions section
                        "extensions" => self.process_message_extensions_start()?,
                        &_ => {}
                    }
                }
                // Process text within tag
                Ok(Event::Text(t)) => self.process_text(t)?,
                Ok(Event::End(e)) => {
                    let tag_name = String::from_utf8_lossy(e.name().as_ref()).to_string();
                    // Pop tag and verify tag consistency
                    self.pop_tag(tag_name.as_str())?;

                    // Clone context stack for safety
                    let context_stack = self.context_stack.context_stack_cloned();

                    match context_stack.last() {
                        // Include
                        Some(XmlParsingContext::Include(include)) => {
                            self.process_include_end(include)?
                        }
                        // Version
                        Some(XmlParsingContext::Version(version)) => {
                            self.process_version_end(*version)?
                        }
                        // Dialect
                        Some(XmlParsingContext::Dialect(dialect)) => {
                            self.process_dialect_end(*dialect)?
                        }

                        // Enum (will be parsed and pushed to results)
                        Some(XmlParsingContext::Enum(xml_enum)) => {
                            self.process_enum_end(xml_enum)?
                        }
                        // Enum entry
                        Some(XmlParsingContext::EnumEntry(entry)) => {
                            self.process_enum_entry_end(entry)?
                        }
                        // Enum entry `MAV_CMD` param
                        Some(XmlParsingContext::EnumEntryMavCmdParam(param)) => {
                            self.process_enum_entry_mav_cmd_param_end(param)?
                        }
                        // Message (will be parsed and pushed to results)
                        Some(XmlParsingContext::Message { msg: xml_msg, .. }) => {
                            self.process_message_end(xml_msg)?
                        }
                        // Message field
                        Some(XmlParsingContext::MessageField(fld)) => {
                            self.process_message_field_end(fld)?
                        }
                        // Message extensions section
                        Some(XmlParsingContext::MessageExtensions) => {
                            self.process_message_extensions_end()?
                        }

                        // Description
                        Some(XmlParsingContext::Description(description)) => {
                            self.process_description_end(description.to_string())?
                        }
                        // Deprecation status
                        Some(XmlParsingContext::Deprecated(deprecated)) => {
                            self.process_deprecated_end(deprecated)?;
                        }
                        // Work in progress status
                        Some(XmlParsingContext::Wip) => self.process_wip_end()?,
                        _ => {}
                    }

                    self.context_stack.pop_tag(tag_name.as_str());
                }
                // There are several other `Event`s we do not consider here
                _ => (),
            }
        }

        Ok(())
    }

    fn process_mavlink_start(&mut self) -> Result<(), XmlParseError> {
        self.context_stack.push(XmlParsingContext::MavLink)
    }

    fn process_include_start(&mut self) -> Result<(), XmlParseError> {
        self.context_stack
            .push(XmlParsingContext::Include("".to_string()))
    }

    fn process_include_end(&mut self, content: &str) -> Result<(), XmlParseError> {
        self.includes.push(content.to_string());
        Ok(())
    }

    fn process_version_start(&mut self) -> Result<(), XmlParseError> {
        self.context_stack.push(XmlParsingContext::Version(0))
    }

    fn process_version_end(&mut self, version: u8) -> Result<(), XmlParseError> {
        self.version = Some(version);
        Ok(())
    }

    fn process_dialect_start(&mut self) -> Result<(), XmlParseError> {
        self.context_stack.push(XmlParsingContext::Dialect(0))
    }

    fn process_dialect_end(&mut self, dialect: u32) -> Result<(), XmlParseError> {
        self.dialect_id = Some(dialect);
        Ok(())
    }

    fn process_enum_start(&mut self, bytes_start: BytesStart) -> Result<(), XmlParseError> {
        let mut name: String = "".to_string();
        let mut description: String = "".to_string();
        let mut bitmask = false;

        for attr in bytes_start.attributes() {
            let attr = attr.unwrap();
            let key = String::from_utf8_lossy(attr.key.as_ref()).to_string();
            let value = String::from_utf8_lossy(attr.value.as_ref()).to_string();

            match key.as_ref() {
                "name" => name = value,
                "description" => description = value,
                "bitmask" => {
                    if value == "true" {
                        bitmask = true
                    }
                }
                &_ => {}
            }
        }

        self.context_stack.push(XmlParsingContext::Enum(XmlEnum {
            name,
            bitmask,
            description,
            entries: HashMap::new(),
            deprecated: None,
            defined_in: vec![self.dialect_name.unwrap().to_string()],
        }))?;

        Ok(())
    }

    fn process_enum_end(&mut self, xml_enum: &XmlEnum) -> Result<(), XmlParseError> {
        let enum_name = xml_enum.name.clone();
        let new_enum = xml_enum.to_enum()?;

        if self.enums.contains_key(&enum_name) {
            let old_enum = self.enums.get(&enum_name).unwrap();
            let mut entries = old_enum.entries().clone();
            let mut defined_in = old_enum.defined_in().clone();
            defined_in.push(self.dialect_name.unwrap().to_string());

            for (entry_name, entry) in new_enum.entries() {
                entries.insert(entry_name.clone(), entry.clone());
            }

            // Insert updated enum
            let updated_enum = Enum::new(
                new_enum.name().clone(),
                new_enum.description().clone(),
                entries,
                new_enum.bitmask(),
                new_enum.deprecated().clone(),
                defined_in,
            );
            self.enums.insert(enum_name.clone(), updated_enum);
        } else {
            // Insert new enum
            self.enums.insert(enum_name, new_enum);
        }

        Ok(())
    }

    fn process_enum_entry_start(&mut self, bytes_start: BytesStart) -> Result<(), XmlParseError> {
        if let Some(XmlParsingContext::Enum(_)) = self.context_stack.last() {
            let mut enum_value = "".to_string();
            let mut name = "".to_string();
            let mut description = "".to_string();
            let mut cmd_flags = XmlEnumEntryMavCmdFlags {
                has_location: None,
                is_destination: None,
                mission_only: None,
            };

            for attr in bytes_start.attributes() {
                let attr = attr.unwrap();
                let key = String::from_utf8_lossy(attr.key.as_ref()).to_string();
                let value = String::from_utf8_lossy(attr.value.as_ref()).to_string();

                match key.as_ref() {
                    "value" => enum_value = value,
                    "name" => name = value,
                    "description" => description = value,
                    "hasLocation" => {
                        cmd_flags.has_location = Some(
                            value
                                .parse::<bool>()
                                .map_err(XmlParseError::EnumEntryMavCmdFlagsInvalidHasLocation)?,
                        )
                    }
                    "isDestination" => {
                        cmd_flags.is_destination = Some(
                            value
                                .parse::<bool>()
                                .map_err(XmlParseError::EnumEntryMavCmdFlagsInvalidIsDestination)?,
                        )
                    }
                    "missionOnly" => {
                        cmd_flags.mission_only = Some(
                            value
                                .parse::<bool>()
                                .map_err(XmlParseError::EnumEntryMavCmdFlagsInvalidMissionOnly)?,
                        )
                    }
                    &_ => {}
                }
            }

            self.context_stack
                .push(XmlParsingContext::EnumEntry(XmlEnumEntry {
                    value: enum_value,
                    name,
                    description,
                    cmd_flags,
                    params: Vec::new(),
                    wip: false,
                    deprecated: None,
                    defined_in: Some(self.dialect_name.unwrap().to_string()),
                }))?;
        }

        Ok(())
    }

    fn process_enum_entry_end(&mut self, entry: &XmlEnumEntry) -> Result<(), XmlParseError> {
        let subject = self
            .context_stack
            .parent_context_mut(XmlParseError::EnumEntryWithoutEnum)?;

        match subject {
            XmlParsingContext::Enum(xml_enum) => {
                xml_enum.entries.insert(entry.name.clone(), entry.clone());
            }
            &mut _ => {}
        }

        Ok(())
    }

    fn process_enum_entry_mav_cmd_param_start(
        &mut self,
        bytes_start: BytesStart,
    ) -> Result<(), XmlParseError> {
        if let Some(XmlParsingContext::EnumEntry(_)) = self.context_stack.last() {
            let mut index = "".to_string();
            let mut description = "".to_string();
            let mut label = None;
            let mut units = None;
            let mut r#enum = None;
            let mut decimal_places = None;
            let mut increment = None;
            let mut min_value = None;
            let mut max_value = None;
            let mut reserved = None;
            let mut default = None;

            for attr in bytes_start.attributes() {
                let attr = attr.unwrap();
                let key = String::from_utf8_lossy(attr.key.as_ref()).to_string();
                let value = String::from_utf8_lossy(attr.value.as_ref()).to_string();

                match key.as_ref() {
                    "index" => index = value,
                    "description" => description = value,
                    "label" => label = Some(value),
                    "units" => units = Some(value),
                    "enum" => r#enum = Some(value),
                    "decimalPlaces" => decimal_places = Some(value),
                    "increment" => increment = Some(value),
                    "minValue" => min_value = Some(value),
                    "maxValue" => max_value = Some(value),
                    "reserved" => reserved = Some(value),
                    "default" => default = Some(value),
                    &_ => {}
                }
            }

            self.context_stack
                .push(XmlParsingContext::EnumEntryMavCmdParam(
                    XmlEnumEntryMavCmdParam {
                        index,
                        description,
                        label,
                        units,
                        r#enum,
                        decimal_places,
                        increment,
                        min_value,
                        max_value,
                        reserved,
                        default,
                    },
                ))?;
        }

        Ok(())
    }

    fn process_enum_entry_mav_cmd_param_end(
        &mut self,
        param: &XmlEnumEntryMavCmdParam,
    ) -> Result<(), XmlParseError> {
        let subject = self
            .context_stack
            .parent_context_mut(XmlParseError::MavCmdParamWithoutEnumEntry)?;

        match subject {
            XmlParsingContext::EnumEntry(xml_enum_entry) => {
                xml_enum_entry.params.push(param.clone());
            }
            &mut _ => {}
        }

        Ok(())
    }

    fn process_deprecated_start(&mut self, bytes_start: BytesStart) -> Result<(), XmlParseError> {
        if let Some(XmlParsingContext::EnumEntry(_)) = self.context_stack.last() {
            let mut since = "".to_string();
            let mut replaced_by = "".to_string();

            for attr in bytes_start.attributes() {
                let attr = attr.unwrap();
                let key = String::from_utf8_lossy(attr.key.as_ref()).to_string();
                let value = String::from_utf8_lossy(attr.value.as_ref()).to_string();

                match key.as_ref() {
                    "since" => since = value,
                    "replaced_by" => replaced_by = value,
                    &_ => {}
                }
            }

            self.context_stack
                .push(XmlParsingContext::Deprecated(XmlDeprecated {
                    since,
                    replaced_by,
                }))?;
        }

        Ok(())
    }

    fn process_deprecated_end(&mut self, deprecated: &XmlDeprecated) -> Result<(), XmlParseError> {
        let subject = self
            .context_stack
            .parent_context_mut(XmlParseError::DeprecationWithoutSubject)?;

        match subject {
            XmlParsingContext::Enum(enm) => enm.deprecated = Some(deprecated.clone()),
            XmlParsingContext::EnumEntry(entry) => entry.deprecated = Some(deprecated.clone()),
            XmlParsingContext::Message { msg, .. } => msg.deprecated = Some(deprecated.clone()),
            &mut _ => {}
        }

        Ok(())
    }

    fn process_description_start(&mut self) -> Result<(), XmlParseError> {
        self.context_stack
            .push(XmlParsingContext::Description("".to_string()))?;

        Ok(())
    }

    fn process_description_end(&mut self, description: String) -> Result<(), XmlParseError> {
        let subject = self
            .context_stack
            .parent_context_mut(XmlParseError::DescriptionWithoutSubject)?;

        match subject {
            XmlParsingContext::Enum(enm) => enm.description = description,
            XmlParsingContext::EnumEntry(entry) => entry.description = description,
            XmlParsingContext::Message { msg, .. } => msg.description = description,
            &mut _ => {}
        }

        Ok(())
    }

    fn process_message_start(&mut self, bytes_start: BytesStart) -> Result<(), XmlParseError> {
        let mut id = "".to_string();
        let mut name = "".to_string();
        let mut description = "".to_string();

        for attr in bytes_start.attributes() {
            let attr = attr.unwrap();
            let key = String::from_utf8_lossy(attr.key.as_ref()).to_string();
            let value = String::from_utf8_lossy(attr.value.as_ref()).to_string();

            match key.as_ref() {
                "id" => id = value,
                "name" => name = value,
                "description" => description = value,
                &_ => {}
            }
        }

        self.context_stack.push(XmlParsingContext::Message {
            msg: XmlMessage {
                id,
                name,
                description,
                fields: vec![],
                wip: false,
                deprecated: None,
                defined_in: Some(self.dialect_name.unwrap().to_string()),
            },
            in_extension_section: false,
        })?;

        Ok(())
    }

    fn process_message_end(&mut self, xml_message: &XmlMessage) -> Result<(), XmlParseError> {
        self.messages.insert(
            xml_message
                .id
                .parse::<MessageId>()
                .map_err(XmlParseError::InvalidMessageId)?,
            xml_message.to_message()?,
        );

        Ok(())
    }

    fn process_message_field_start(
        &mut self,
        bytes_start: BytesStart,
    ) -> Result<(), XmlParseError> {
        if let Some(XmlParsingContext::Message { .. }) = self.context_stack.last() {
            let mut name = "".to_string();
            let mut description = "".to_string();
            let mut field_type = "".to_string();
            let mut r#enum: Option<String> = None;
            let mut units = None;
            let mut bitmask = false;
            let mut print_format: Option<String> = None;
            let mut default: Option<String> = None;
            let mut invalid: Option<String> = None;
            let mut instance = false;

            for attr in bytes_start.attributes() {
                let attr = attr.unwrap();
                let key = String::from_utf8_lossy(attr.key.as_ref()).to_string();
                let value = String::from_utf8_lossy(attr.value.as_ref()).to_string();

                match key.as_ref() {
                    "name" => name = value,
                    "description" => description = value,
                    "type" => field_type = value,
                    "enum" => r#enum = Some(value),
                    "units" => units = Some(value),
                    "bitmask" => {
                        bitmask = value.parse::<bool>().map_err(|err| {
                            XmlParseError::InvalidMessageFieldInstance(err.clone())
                        })?
                    }
                    "print_format" => print_format = Some(value),
                    "default" => default = Some(value),
                    "invalid" => invalid = Some(value),
                    "instance" => {
                        instance = value.parse::<bool>().map_err(|err| {
                            XmlParseError::InvalidMessageFieldInstance(err.clone())
                        })?
                    }
                    &_ => {}
                }
            }

            self.context_stack
                .push(XmlParsingContext::MessageField(XmlMessageField {
                    name,
                    description,
                    field_type,
                    r#enum,
                    units,
                    bitmask,
                    print_format,
                    default,
                    invalid,
                    instance,
                    extension: false, // This will be filled later from `<extensions/> tag`
                }))?;
        }

        Ok(())
    }

    fn process_message_field_end(&mut self, fld: &XmlMessageField) -> Result<(), XmlParseError> {
        let subject = self
            .context_stack
            .parent_context_mut(XmlParseError::MessageFieldWithoutMessage)?;

        match subject {
            XmlParsingContext::Message { msg: message, .. } => message.fields.push(fld.clone()),
            &mut _ => {}
        }

        Ok(())
    }

    fn process_wip_start(&mut self) -> Result<(), XmlParseError> {
        self.context_stack.push(XmlParsingContext::Wip)?;

        Ok(())
    }

    fn process_wip_end(&mut self) -> Result<(), XmlParseError> {
        let subject = self
            .context_stack
            .parent_context_mut(XmlParseError::WipWithoutSubject)?;

        match subject {
            XmlParsingContext::Message {
                msg: xml_message, ..
            } => xml_message.wip = true,
            XmlParsingContext::EnumEntry(xml_enum) => xml_enum.wip = true,
            &mut _ => {}
        }

        Ok(())
    }

    fn process_message_extensions_start(&mut self) -> Result<(), XmlParseError> {
        self.context_stack
            .push(XmlParsingContext::MessageExtensions)?;

        Ok(())
    }

    fn process_message_extensions_end(&mut self) -> Result<(), XmlParseError> {
        let subject = self
            .context_stack
            .parent_context_mut(XmlParseError::MessageExtensionsWithoutMessage)?;

        match subject {
            XmlParsingContext::Message {
                msg: _,
                in_extension_section: in_ext,
            } => *in_ext = true,
            &mut _ => {}
        }

        Ok(())
    }

    fn process_text(&mut self, bytes_text: BytesText) -> Result<(), XmlParseError> {
        match self.context_stack.last() {
            Some(XmlParsingContext::Description(_)) => {}
            Some(XmlParsingContext::MessageField(_)) => {}
            Some(XmlParsingContext::EnumEntryMavCmdParam(_)) => {}
            Some(XmlParsingContext::Include(_)) => {}
            Some(XmlParsingContext::Version(_)) => {}
            Some(XmlParsingContext::Dialect(_)) => {}
            _ => return Ok(()),
        }

        let text = String::from_utf8_lossy(bytes_text.as_ref()).to_string();
        let subject = self
            .context_stack
            .last_mut()
            .ok_or(XmlParseError::DescriptionWithoutSubject)?;

        match subject {
            XmlParsingContext::Include(s) => *s = text,
            XmlParsingContext::Version(s) => {
                *s = text
                    .parse::<u8>()
                    .map_err(XmlParseError::VersionParseFailed)?
            }
            XmlParsingContext::Dialect(s) => {
                *s = text
                    .parse::<u32>()
                    .map_err(XmlParseError::DialectIdParseFailed)?
            }
            XmlParsingContext::Description(s) => *s = text,
            XmlParsingContext::MessageField(fld) => fld.description = text,
            XmlParsingContext::EnumEntryMavCmdParam(param) => param.description = text,
            &mut _ => {}
        }

        Ok(())
    }

    fn clear(&mut self) {
        self.includes = Vec::new();
        self.version = None;
        self.dialect_id = None;

        self.tag_stack = Vec::new();
        self.context_stack = XmlParsingContextStack::new();
    }

    fn push_tag(&mut self, opening_tag: &str) -> Result<(), XmlParseError> {
        self.tag_stack.push(opening_tag.to_string());
        Ok(())
    }

    fn pop_tag(&mut self, closing_tag: &str) -> Result<(), XmlParseError> {
        let last_opened_tag = self.tag_stack.last().map(|t| t.to_string());
        match last_opened_tag {
            Some(previous_tag) if previous_tag == closing_tag => {}
            _ => {
                return Err(XmlParseError::InvalidClosingTag {
                    opened_with: last_opened_tag,
                    closed_with: closing_tag.to_string(),
                })
            }
        }

        self.tag_stack.pop();
        Ok(())
    }
}