#![feature(path_add_extension)]

mod generate_html;
pub use generate_html::*;

use markdown::*;
use vagabond::*;


const NORMAL: &str = "\x1b[0m";
const BOLD:   &str = "\x1b[1m";
const WHITE:  &str = "\x1b[37m";
const RED:    &str = "\x1b[31m";
const YELLOW: &str = "\x1b[33m";
const BLUE:   &str = "\x1b[34m";

static mut VERBOSE: bool = false;
#[macro_export] macro_rules! verbose {
    ($($tokens:tt)*) => { if unsafe { VERBOSE } {
        eprint!("{BOLD}{BLUE}[INFO]{NORMAL}: "); eprint!($($tokens)*);
        eprintln!("{NORMAL}");
    } };
}
#[macro_export] macro_rules! warn {
    ($($tokens:tt)*) => {{
        eprint!("{BOLD}{YELLOW}[WARNING]{NORMAL}{WHITE}: "); eprint!($($tokens)*);
        eprintln!("{NORMAL}");
    }};
}
#[macro_export] macro_rules! error {
    ($($tokens:tt)*) => {{
        eprint!("{BOLD}{RED}[ERROR]{WHITE}: "); eprint!($($tokens)*);
        eprintln!("{NORMAL}"); std::process::exit(1);
    }};
}

fn main() {
    let args = Arguments::from_env_or_exit();
    if args.version {
        let version = env!("CARGO_PKG_VERSION");
        eprintln!("toaster, version {version}");
        std::process::exit(0);
    }
    if args.verbose {
        unsafe { VERBOSE = true; }
    }
    if args.source.is_none() || args.destination.is_none() {
        error!("Provide a source directory and a destination directory.")
    }
    let source_directory = args.source.unwrap().canonicalize().unwrap();
    let destination_directory = args.destination.unwrap();

    let mut website = Website {
        source_files: Vec::new(),
        static_files: Vec::new(),
        name: match Entry::from_path(&source_directory) {
            Ok(entry) => entry.name,
            Err(err) => error!("Couldn't open {:?}: {:?}", &source_directory, err),
        },
        error: false,
    };


    // Collect all website files.
    match traverse_directory(&source_directory) {
        Ok(entries) => for entry in entries {
            // Ignore dot files.
            if entry.name.starts_with(".") {
                continue;
            }
            // Generate name, stripping any leading digit sequence.
            let (mut name, extension) = entry.split_name();
            if let Some((prefix, suffix)) = name.split_once(' ') {
                if prefix.chars().all(|c| "0123456789-".contains(c)) {
                    name = suffix.to_string();
                }
            }
            // Generate full URL with stripped name, no extension.
            let source_path = entry.original_path;
            let relative_path = source_path.strip_prefix(&source_directory).unwrap_or_else(
                // Probably unreachable.
                |_| error!("Path doesn't start with {:?}: {:?}", source_directory, source_path));
            let mut full_url = String::new();
            let mut components: Vec<_> = relative_path.components().collect();
            components.pop();  // Remove file segment, use the stripped name instead.
            for c in components {
                full_url.push_str(&make_url_safe(&c.as_os_str().to_string_lossy()));
                full_url.push('/')
            };
            let parent_url = full_url.clone();
            full_url.push_str(&make_url_safe(&name));


            if extension == "md" {
                // Rename and relocate index files.
                let mut file_url = make_url_safe(&name);
                if file_url == "+index" {
                    let components: Vec<_> = relative_path.components().collect();
                    if components.len() == 1 {
                        name = String::from("Home");
                        file_url = String::from("index");
                        full_url = String::from("index");
                    } else {
                        let parent = components[components.len()-2];
                        let parent_string = parent.as_os_str().to_string_lossy().to_string();
                        name = parent_string;
                        file_url = make_url_safe(&name);
                        full_url.clear();
                        for c in &components[..components.len()-2] {
                            full_url.push_str(&make_url_safe(&c.as_os_str().to_string_lossy()));
                            full_url.push('/')
                        };
                        full_url.push_str(&file_url);
                    }
                }
                // Load and parse the markdown.
                let markdown = std::fs::read_to_string(&source_path).unwrap();
                let document = MarkdownDocument::from_str(&markdown);
                let headings = document.blocks.iter().filter_map(|block| match block {
                    Block::Heading { line, .. } => Some(make_url_safe(&line.to_string())),
                    _ => None,
                }).collect();
                website.source_files.push(
                    SourceFile { name, parent_url, file_url, full_url, source_path, document, headings });
            } else {
                full_url.push('.'); full_url.push_str(&extension);
                website.static_files.push(StaticFile { full_url, source_path });
            }
        }
        Err(err) => error!("Could not read from source directory: {:?}", err),
    }

    let mut destination = destination_directory.clone();
    destination.push(make_url_safe(&website.name));

    for source_file in &website.source_files {
        let mut destination = destination.clone();
        destination.push(&source_file.full_url);
        // Convert document to different formats.
        if args.html {
            let html = generate_html(&source_file.document, source_file, &website);
            write_file(&html, &destination, "html");
        }
        // Copy original markdown file.
        destination.add_extension("md");
        verbose!("Copying original markdown file to {destination:?}");
        copy(&source_file.source_path, &destination).unwrap();
    }

    for static_file in &website.static_files {
        let mut destination = destination.clone();
        destination.push(&static_file.full_url);
        verbose!("Copying static file to {destination:?}");
        make_parent_directory(&destination).unwrap();
        copy(&static_file.source_path, &destination).unwrap();
    }
}



pub fn write_file(text: &str, destination: &PathBuf, ext: &str) {
    let mut destination = destination.clone();
    destination.add_extension(ext);
    verbose!("Generating {destination:?}");
    make_parent_directory(&destination).unwrap();
    write_to_file(destination, text).unwrap();
}

pub fn make_url_safe(text: &str) -> String {
    text.to_ascii_lowercase().chars().filter_map(|c|
        if c.is_alphanumeric() || "-_~.+/#".contains(c) { Some(c) }
        else if c == ' ' { Some('-') }
        else { None } )
    .collect()
}


pub struct Website {
    pub name: String,
    pub source_files: Vec<SourceFile>,
    pub static_files: Vec<StaticFile>,
    pub error: bool,
}

impl Website {
    // Ext is extension without a dot.
    // Checks if a relative link to an internal page name can be reached from
    // the current page, and returns a resolved absolute link to the page with extension.
    pub fn has_page(&self, from: &SourceFile, path: &str, ext: &str) -> Option<String> {
        // Remove heading fragment and file extension.
        let (path, heading) = match path.rsplit_once('#') {
            Some((path, heading)) => match heading.is_empty() {
                true => (path, None),
                false => (path, Some(heading)),
            }
            None => (path, None),
        };
        let path = path.strip_suffix(&format!(".{ext}")).unwrap_or(path);

        // Attach parent of current page to given path.
        let directory = match from.parent_url.rsplit_once('/') {
            Some((parent, _)) => parent,
            None => &from.parent_url,
        };
        let full_path = match path.starts_with("/") {
            true => path.to_string(),
            false => format!("{directory}/{path}"),
        };

        // Remove relative portions of path.
        let segments: Vec<&str> = full_path.split("/")
            .filter(|seg| !seg.is_empty() && *seg != ".")
            .collect();
        let mut reduced_segments: Vec<&str> = segments.windows(2)
            .filter(|w| w[1] != "..")
            .map(|w| w[1])
            .collect();
        // The first segment is always skipped by the previous step.
        if !segments.is_empty() && segments.get(1) != Some(&"..") {
            if segments[0] != ".." {
                reduced_segments.insert(0, segments[0]);
            }
        }
        let path = reduced_segments.join("/");

        for source_file in &self.source_files {
            if source_file.full_url == path {
                if let Some(heading) = heading {
                    if !source_file.headings.contains(&make_url_safe(heading)) {
                        warn!("Page {:?} contains link to nonexistent heading {heading:?} on page {path:?}", from.name);
                    }
                }
                return Some(format!("{path}.{ext}"));
            }
        }
        return None;
    }
}

pub struct SourceFile {
    pub name: String,
    pub parent_url: String,  // URL base of child pages
    pub file_url: String,    // URL file segment, no extension
    pub full_url: String,    // URL full path, no extension
    pub source_path: PathBuf,
    pub document: MarkdownDocument,
    pub headings: Vec<String>,
}

impl SourceFile {
    pub fn back_string(&self) -> String {
        let mut back = String::new();
        for c in self.full_url.chars() {
            if c == '/' {
                back.push_str("../");
            }
        }
        return back;
    }
}

pub struct StaticFile {
    pub full_url: String,  // URL full path, with extension
    pub source_path: PathBuf,
}

xflags::xflags! {
    /// Generate a website from a structured directory of markdown files.
    cmd arguments {
        /// Source directory with markdown files
        optional source: PathBuf
        /// Path to output directory
        optional destination: PathBuf
        /// Generate HTML output
        optional --html
        /// Generate Gemtext output
        optional --gmi
        /// Print information as each file is parsed
        optional -v, --verbose
        /// Print the program version and exit
        optional --version
    }
}