use eyre::{eyre, Result};
use gumdrop::Options;
use obsidian_export::{ExportError, Exporter, FrontmatterStrategy, WalkOptions};
use std::path::PathBuf;

#[derive(Debug, Options)]
struct Opts {
    #[options(help = "Display program help")]
    help: bool,

    #[options(help = "Source file containing reference", free, required)]
    source: Option<PathBuf>,

    #[options(help = "Destination file being linked to", free, required)]
    destination: Option<PathBuf>,

    #[options(
        help = "Frontmatter strategy (one of: always, never, auto)",
        no_short,
        long = "frontmatter",
        parse(try_from_str = "frontmatter_strategy_from_str"),
        default = "auto"
    )]
    frontmatter_strategy: FrontmatterStrategy,

    #[options(
        no_short,
        help = "Read ignore patterns from files with this name",
        default = ".export-ignore"
    )]
    ignore_file: String,

    #[options(no_short, help = "Export hidden files", default = "false")]
    hidden: bool,

    #[options(no_short, help = "Disable git integration", default = "false")]
    no_git: bool,

    #[options(no_short, help = "Don't process embeds recursively", default = "false")]
    no_recursive_embeds: bool,
}

fn frontmatter_strategy_from_str(input: &str) -> Result<FrontmatterStrategy> {
    match input {
        "auto" => Ok(FrontmatterStrategy::Auto),
        "always" => Ok(FrontmatterStrategy::Always),
        "never" => Ok(FrontmatterStrategy::Never),
        _ => Err(eyre!("must be one of: always, never, auto")),
    }
}

fn main() -> Result<()> {
    let args = Opts::parse_args_default_or_exit();
    let source = args.source.unwrap();
    let destination = args.destination.unwrap();

    let mut walk_options = WalkOptions::default();
    walk_options.ignore_filename = &args.ignore_file;
    walk_options.ignore_hidden = !args.hidden;
    walk_options.honor_gitignore = !args.no_git;

    let mut exporter = Exporter::new(source, destination);
    exporter.frontmatter_strategy(args.frontmatter_strategy);
    exporter.process_embeds_recursively(!args.no_recursive_embeds);
    exporter.walk_options(walk_options);

    if let Err(err) = exporter.run() {
        match err {
            ExportError::FileExportError {
                ref path,
                ref source,
            } => match &**source {
                // An arguably better way of enhancing error reports would be to construct a custom
                // `eyre::EyreHandler`, but that would require a fair amount of boilerplate and
                // reimplementation of basic reporting.
                ExportError::RecursionLimitExceeded { file_tree } => {
                    eprintln!(
                        "Error: {:?}",
                        eyre!(
                            "'{}' exceeds the maximum nesting limit of embeds",
                            path.display()
                        )
                    );
                    eprintln!("\nFile tree:");
                    for (idx, path) in file_tree.iter().enumerate() {
                        eprintln!("  {}-> {}", "  ".repeat(idx), path.display());
                    }
                    eprintln!("\nHint: Ensure notes are non-recursive, or specify --no-recursive-embeds to break cycles")
                }
                _ => eprintln!("Error: {:?}", eyre!(err)),
            },
            _ => eprintln!("Error: {:?}", eyre!(err)),
        };
        std::process::exit(1);
    };

    Ok(())
}