// Read a Ksudoku's XML save file.
use std::collections::HashMap;
use std::error;
// use std::fmt;
use std::fs::File;
use std::io::BufReader;
use xml::reader::{EventReader, XmlEvent};
use xml::writer::XmlEvent as WrXmlEvent;
use xml::EmitterConfig;

/*
What I want from load_ksudoku:

  - Puzzle string
  - Solution string (so I can validate it/check my code)
  - specific-type & type (combined as a string is ok - I think)
  - order (as a number)

I get values (the puzzle), I also need solution.

Having order will allow me to use AnyBoard::new(order) and load it up.
*/

#[derive(Debug)]
pub struct Ksudoku {
    /// puzzle string:
    /// _ is blank, starts with 'b' (for 1), 'c' for 2.
    pub puzzle: String,
    /// This contains the solution to the puzzle.
    pub solution: String,
    /// "Plain"
    pub specific_type: String,
    /// "sudoku"
    pub puzzle_type: String,
    /// Puzzle width (9, 16, 25).
    pub order: u8,
}

impl Default for Ksudoku {
    fn default() -> Self {
        Ksudoku {
            puzzle: String::new(),
            solution: String::new(),
            specific_type: String::from("Plain"),
            puzzle_type: String::from("sudoku"),
            order: 0,
        }
    }
}

/// Load ksudoku file, returning Ksudoku structure.
/// - It is up to the caller to determine if they can handle the types
///   and size (order).
pub fn load_ksudoku(filename: std::path::PathBuf) -> Result<Ksudoku, Box<dyn error::Error>> {
    let fh = File::open(filename)?;
    let buffer = BufReader::new(fh);
    let parser = EventReader::new(buffer);
    let mut element_name: String = String::new();
    let mut details = Ksudoku::default();

    for e in parser {
        match e {
            Ok(XmlEvent::StartElement {
                name, attributes, ..
            }) => {
                element_name = name.local_name.clone();
                if element_name == "graph" {
                    // Check the attributes here
                    // <graph specific-type="Plain" type="sudoku" order="9"/>
                    // {"specific-type": "Plain", "type": "sudoku", "order": "9"}

                    let mut attrs: HashMap<String, String> = HashMap::new();

                    for a in attributes {
                        attrs.insert(a.name.to_string(), a.value);
                    }

                    let blank = String::new();

                    details.specific_type = attrs
                        .get(&"specific-type".to_string())
                        .unwrap_or(&blank)
                        .clone();
                    details.puzzle_type = attrs.get(&"type".to_string()).unwrap_or(&blank).clone();
                    let order = attrs.get(&"order".to_string()).unwrap_or(&blank).clone();

                    if !order.is_empty() {
                        let r = order.parse::<u8>();
                        if r.is_ok() {
                            details.order = r.unwrap();
                        } else {
                            // Failed to convert order to u8...
                            return Err(Box::new(r.unwrap_err()));
                        }
                    }
                }
            }
            Ok(XmlEvent::Characters(text)) => {
                if element_name == "values" {
                    details.puzzle = text.clone();
                }
                if element_name == "solution" {
                    details.solution = text.clone();
                }
            }
            Err(e) => {
                return Err(Box::new(e));
            }
            _ => {}
        }
    }

    Ok(details)
}

/// Write out a ksudoku puzzle file
pub fn save_ksudoku(
    filename: std::path::PathBuf,
    data: &Ksudoku,
) -> Result<(), Box<dyn error::Error>> {
    let fh = File::create(filename)?;
    let mut writer = EmitterConfig::new().perform_indent(true).create_writer(fh);

    let mut event: WrXmlEvent = WrXmlEvent::start_element("ksudoku").into();
    writer.write(event)?;
    event = WrXmlEvent::start_element("game")
        .attr("had-help", "0")
        .attr("msecs-elapsed", "0")
        .into();
    writer.write(event)?;
    event = WrXmlEvent::start_element("puzzle").into();
    writer.write(event)?;

    // Convert order to a string.
    let order = data.order.to_string();

    event = WrXmlEvent::start_element("graph")
        .attr("specific-type", &data.specific_type)
        .attr("type", &data.puzzle_type)
        .attr("order", &order)
        .into();
    writer.write(event)?;
    event = WrXmlEvent::end_element().into();
    writer.write(event)?;

    // values (puzzle)
    event = WrXmlEvent::start_element("values").into();
    writer.write(event)?;
    event = WrXmlEvent::characters(&data.puzzle).into();
    writer.write(event)?;
    event = WrXmlEvent::end_element().into();
    writer.write(event)?;

    // solution
    event = WrXmlEvent::start_element("solution").into();
    writer.write(event)?;
    event = WrXmlEvent::characters(&data.solution).into();
    writer.write(event)?;
    event = WrXmlEvent::end_element().into();
    writer.write(event)?;

    // Apparently, the events are consumed...

    event = WrXmlEvent::end_element().into();
    writer.write(event)?;
    event = WrXmlEvent::end_element().into();
    writer.write(event)?;
    event = WrXmlEvent::end_element().into();
    writer.write(event)?;

    Ok(())
}

#[cfg(test)]

mod tests {
    use crate::ksudoku::*;
    use crate::sudoku::*;
    use std::path::PathBuf;

    fn test_files_path() -> PathBuf {
        let mut d = PathBuf::from(env!("CARGO_MANIFEST_DIR"));
        d.push("test_files");
        d
    }

    #[test]
    fn load_puzzles() {
        let mut testfile = test_files_path();
        testfile.push("missing");

        let result = load_ksudoku(testfile);
        assert!(result.is_err());

        let mut testfile = test_files_path();
        testfile.push("9-puzzle");

        let result = load_ksudoku(testfile);
        assert!(result.is_ok());
        let result = result.unwrap();
        assert!(result.puzzle_type == "sudoku");
        assert!(result.specific_type == "Plain");

        let size = (result.order as f64).sqrt() as u8;
        let mut board = AnyBoard::new(size);
        let load = board.load_from_tld('b', '_', &result.puzzle);
        assert!(load.is_ok());

        // Ok, puzzle is loaded!
        let strings = board.to_strings();
        assert_eq!(
            strings,
            vec![
                "  4   8  ",
                " 6  1  2 ",
                "3  9 5  6",
                "  72 16  ",
                " 3     9 ",
                "  18 35  ",
                "9  3 6  2",
                " 4  5  8 ",
                "  3   7  ",
            ]
        );

        let mut testfile = test_files_path();
        testfile.push("16-puzzle");

        let result = load_ksudoku(testfile);
        assert!(result.is_ok());
        let result = result.unwrap();
        assert!(result.puzzle_type == "sudoku");
        assert!(result.specific_type == "Plain");

        let size = (result.order as f64).sqrt() as u8;
        let mut board = AnyBoard::new(size);
        let load = board.load_from_tld('b', '_', &result.puzzle);
        assert!(load.is_ok());

        // Ok, puzzle is loaded!
        let strings: Vec<String> = board.to_strings();
        assert_eq!(
            strings,
            vec![
                " D    O    C  IN",
                "A  ENC   IL     ",
                "NG  AP   J MHC  ",
                "  P H   D A  FOL",
                "IOHKFB  A   L  P",
                " BN  M E L ID   ",
                "LE  O AN K BC   ",
                " C    H    JO EF",
                "EN GP    A    F ",
                "   OG J IM L  NC",
                "   MK B C N  PG ",
                "C  L   F  PEMIKO",
                "OPC  N H   F J  ",
                "  EHJ I   MA  CK",
                "     FM   IPA  D",
                "FM  L    H    P "
            ]
        );
        // board.display();

        let mut testfile = test_files_path();
        testfile.push("25-puzzle");

        let result = load_ksudoku(testfile);
        assert!(result.is_ok());
        let result = result.unwrap();
        assert!(result.puzzle_type == "sudoku");
        assert!(result.specific_type == "Plain");

        let size = (result.order as f64).sqrt() as u8;
        let mut board = AnyBoard::new(size);
        let load = board.load_from_tld('b', '_', &result.puzzle);
        assert!(load.is_ok());

        // Ok, puzzle is loaded!
        // board.display();
        let strings: Vec<String> = board.to_strings();
        assert_eq!(
            strings,
            vec![
                " T DPF    Y H R    WSX L ",
                "L QF     J X C G     UB D",
                " CK S LNRP  G  UTQO H MA ",
                "JG   H S XELDUPM F B   RT",
                "Y N RQ UCDOK AISJL HP G E",
                "F  OA N UK VQI HY B DT  C",
                "  S  A C VUE GJQ N I  R  ",
                "  CPD JGMIA   OELSU VBK  ",
                "  G LE D BHT XMW K PI Y  ",
                " EXIBOWFLY     VAMTJUGQS ",
                "G  HV TMI       EWF BR  O",
                " A JFUK W  P D  M GLXE N ",
                "R LN G             O QI F",
                " S TCYP B  H O  X JNAK M ",
                "M  XK ALJ       UHQ GP  Y",
                " VTRYBSEFM     KWOICJNLG ",
                "  U XD J WCN RTA E QY P  ",
                "  HQN COVTJ   EBGDL WSF  ",
                "  F  X Y LWB SVJ R T  O  ",
                "E  CJ R AN GOF XH V MD  B",
                "S V OI ANHDC TGLQJ YF X P",
                "CX   L K RFUYBWO V A   DQ",
                " FR H DQOC  K  INBW T UY ",
                "T JL     G I P F     OC W",
                " B KMV    Q J H    GRI E "
            ]
        );
    }
}