//! A "Markdown" parser and HTML generator. Part of a static site generator `marksmith-rs`.
//! Not following any standards, only vibes.

#![deny(dead_code, unused_imports)]
#![allow(clippy::needless_pass_by_value)]

use fstools::crawl_fs;
use parser::parse;
use slogger::{Level, log};
use std::{
    fmt::Display,
    fs::{self, File},
    io::Write,
    path::PathBuf,
    time::Instant,
};
use to_html::ToHtml;

pub mod ast;
mod parse_trait;
pub mod parser;
pub mod to_html;

#[derive(Debug)]
pub struct MdParseError {
    file: Option<PathBuf>,
    line: Option<usize>,
    //col: Option<usize>,
    expected: String,
    got: String,
}

impl MdParseError {
    pub fn new(expected: impl ToString, got: impl ToString) -> Self {
        Self {
            file: None,
            line: None,
            //col: None,
            expected: expected.to_string(),
            got: got.to_string(),
        }
    }

    pub fn from_line(line: usize, expected: impl ToString, got: impl ToString) -> Self {
        Self {
            file: None,
            line: Some(line),
            //col: None,
            expected: expected.to_string(),
            got: got.to_string(),
        }
    }

    /*
    pub fn from_col(col: usize, expected: impl ToString, got: impl ToString) -> Self {
        Self {
            file: None,
            line: None,
            col: Some(col),
            expected: expected.to_string(),
            got: got.to_string(),
        }
    }
    */

    #[must_use]
    pub fn set_line(self, line: usize) -> Self {
        Self {
            file: self.file,
            line: Some(line),
            //col: self.col,
            expected: self.expected,
            got: self.got,
        }
    }

    #[must_use]
    pub fn set_file(self, file: PathBuf) -> Self {
        Self {
            file: Some(file),
            line: self.line,
            //col: self.col,
            expected: self.expected,
            got: self.got,
        }
    }
}

impl Display for MdParseError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        // no error message :/
        let file = self.file.clone().unwrap_or("<unknown>".into());
        write!(
            f,
            "Parse error in '{}' on line {}: expected '{}', got '{}'",
            file.display(),
            self.line.unwrap_or(0),
            //self.col.unwrap_or(0),
            self.expected,
            self.got
        )
    }
}

impl std::error::Error for MdParseError {}

#[derive(Debug)]
pub enum Error {
    FSError(String),
    Parse(MdParseError),
}

impl Display for Error {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "{:?}", &self)
    }
}

impl From<MdParseError> for Error {
    fn from(value: MdParseError) -> Self {
        Error::Parse(value)
    }
}

impl std::error::Error for Error {}

type Result<T> = std::result::Result<T, crate::Error>;

/// Takes two directories and a force flag as parameters, generates html files to the outdir in the
/// same directory structure as the md files in indir.
///
/// # Errors
/// Anything wrong with reading files from the directories or parsing the files.
pub fn generate(indir: &PathBuf, outdir: &PathBuf, force: bool) -> Result<()> {
    let start_time = Instant::now();
    let mut generated_files = 0;

    if !indir.is_dir() {
        Err(Error::FSError("In directory not found".to_string()))?;
    }
    if !outdir.is_dir() {
        Err(Error::FSError("Out directory not found".to_string()))?;
    }
    let files = crawl_fs(indir);

    for path in files {
        let fullpath = indir.as_path().join(&path);

        // read and parse md file
        let content = fs::read_to_string(&fullpath)
            .map_err(|_e| Error::FSError(format!("File `{}` read error", path.display())))?;
        let html = parse(&content)?.to_html();

        // write html data to file
        let mut newpath = outdir.to_owned();
        newpath.push(&path);
        newpath.set_extension("html");

        // check if path exists
        if newpath.exists() {
            // remove if is file and if force, otherwise error
            if newpath.is_file() {
                if force {
                    fs::remove_file(&newpath).map_err(|_e| {
                        Error::FSError(format!("File `{}` deleting not allowed", newpath.display()))
                    })?;
                } else {
                    Err(Error::FSError(
                        "File overwrite denied, enable force overwrite".to_string(),
                    ))?;
                }
            } else {
                Err(Error::FSError(format!(
                    "Directory `{}` in place of file in out directory",
                    newpath.display()
                )))?;
            }
        }

        //println!("About to write file '{}'", newpath.display());

        let parent = newpath.parent().ok_or(Error::FSError(format!(
            "Access to parent directory of `{}` denied",
            newpath.display()
        )))?;
        fs::create_dir_all(parent)
            .map_err(|_e| Error::FSError("Creating directory tree failed".to_string()))?;
        let mut newfile = File::create_new(&newpath).map_err(|_e| {
            Error::FSError(format!("Creating file `{}` failed", &newpath.display()))
        })?;

        newfile.write(html.as_bytes()).map_err(|_e| {
            Error::FSError(format!("Writing to file `{}` failed", newpath.display()))
        })?;

        log!(
            Level::Debug,
            "File `{}` generation to `{}` successful",
            path.display(),
            newpath.display()
        );
        generated_files += 1;
    }

    let time = start_time.elapsed();

    let time_report = if time.as_micros() < 10000 {
        format!("{} μs", time.as_micros())
    } else {
        format!("{} ms", time.as_millis())
    };

    log!(
        Level::Info,
        "Generated {} files in {} without reported errors",
        generated_files,
        time_report
    );

    Ok(())
}