mod id;
pub mod utils;

pub use id::ID;

use std::convert::TryInto;
use thiserror::Error;

#[derive(Error, Debug)]
pub enum Error {
    #[error("Data could not be parsed as an integer.")]
    InvalidInteger,
}

/// Hotline defines 3 data types in the wire format:
/// 1) "integer" (16-bit or 32-bit, determined by magnitude)
/// 2) "string" (ASCII)
/// 3) "binary"
#[derive(Debug, Clone)]
pub enum Value {
    Integer(u32),
    Text(String),
    Binary(Vec<u8>),
}

/// A single Hotline field: an ID plus a typed value.
#[derive(Debug, Clone)]
pub struct Field {
    pub id: ID,
    pub value: Value,
}

/// Parse the field data into the correct `Value` type based on the `id`.
///
/// # Errors
/// If an Int can't be parsed, it'll return an `InvalidInteger` error.
pub fn parse_field_value(id: ID, data: &[u8]) -> Result<Value, Error> {
    use Value::{Binary, Integer, Text};
    use ID::{
        AutomaticResponse, ChatID, ChatOptions, ChatSubject, CommunityBannerID, Data, ErrorText,
        FileComment, FileCreateDate, FileCreatorString, FileModifyDate, FileName, FileNameWithInfo,
        FileNewName, FileNewPath, FilePath, FileResumeData, FileSize, FileType, FileTypeString,
        FileXferOptions, FolderItemCount, LegacyNewsCategoryListData, NewsArticle1stChildArticle,
        NewsArticleData, NewsArticleDataFlavor, NewsArticleDate, NewsArticleFlags, NewsArticleID,
        NewsArticleListData, NewsArticleNextArticle, NewsArticleParentArticle, NewsArticlePoster,
        NewsArticlePrevArticle, NewsArticleRecurseDel, NewsArticleTitle, NewsCategoryGUID,
        NewsCategoryListData, NewsCategoryName, NewsPath, NoServerAgreement, Options,
        QuotingMessage, ReferenceNumber, ServerAgreement, ServerBanner, ServerBannerType,
        ServerBannerUrl, ServerName, TransferSize, Unknown, UserAccess, UserAlias, UserFlags,
        UserID, UserIconID, UserLogin, UserName, UserNameWithInfo, UserPassword, Version,
        WaitingCount,
    };

    match id {
        // Integers
        UserID
        | UserIconID
        | ReferenceNumber
        | TransferSize
        | ChatOptions
        | UserFlags
        | Options
        | ChatID
        | WaitingCount
        | ServerBannerType
        | NoServerAgreement
        | Version
        | CommunityBannerID
        | FileSize
        | NewsArticleID
        | NewsArticlePrevArticle
        | NewsArticleNextArticle
        | NewsArticleFlags
        | NewsArticleParentArticle
        | NewsArticle1stChildArticle
        | NewsArticleRecurseDel
        | FolderItemCount => {
            // Convert the data to an integer (u32).
            // Hotline protocol can store 16-bit or 32-bit depending on magnitude,
            // but on the wire we need to detect it. For simplicity here,
            // we'll parse up to 4 bytes. If data is 2 bytes, parse as 16-bit.
            // If 4 bytes, parse as 32-bit. If it's not 2 or 4, we do best-effort.

            let len = data.len();
            if len == 2 {
                data.try_into()
                    .map(u16::from_be_bytes)
                    .map(u32::from)
                    .map(Integer)
                    .map_err(|_| Error::InvalidInteger)
            } else if len == 4 {
                data.try_into()
                    .map(u32::from_be_bytes)
                    .map(Integer)
                    .map_err(|_| Error::InvalidInteger)
            } else {
                Err(Error::InvalidInteger)
            }
        }

        // Strings
        UserName
        | UserLogin
        | UserPassword
        | ChatSubject
        | ServerAgreement
        | FileName
        | FileTypeString
        | FileCreatorString
        | FileComment
        | FileNewName
        | AutomaticResponse
        | ServerName
        | NewsCategoryName
        | NewsArticleDataFlavor
        | NewsArticleTitle
        | NewsArticlePoster => {
            let s = String::from_utf8_lossy(data).to_string();
            Ok(Text(s))
        }

        // Some are definitely “binary,” but might happen to contain text:
        ErrorText
        | Data
        | ServerBanner
        | ServerBannerUrl
        | FileNameWithInfo
        | FilePath
        | FileResumeData
        | FileXferOptions
        | FileCreateDate
        | FileModifyDate
        | FileNewPath
        | FileType
        | QuotingMessage
        | UserAccess
        | UserAlias
        | UserNameWithInfo
        | NewsCategoryGUID
        | LegacyNewsCategoryListData
        | NewsArticleListData
        | NewsCategoryListData
        | NewsPath
        | NewsArticleDate
        | NewsArticleData
        | Unknown(_) => Ok(Binary(data.to_vec())),
    }
}