#![feature(path_add_extension)]

mod formats;
mod types;
mod stages;
pub use formats::*;
pub use types::*;
pub use stages::*;

use assembler::*;
use log::*;
use switchboard::*;

use std::io::Read;
use std::io::Write;


pub const RETURN_MODE:    u8 = 0x80;
pub const WIDE_MODE:      u8 = 0x40;
pub const IMMEDIATE_MODE: u8 = 0x20;


pub fn assemble(mut args: Switchboard, invocation: &str) {
    args.positional("source");
    args.positional("destination");
    args.named("extension").default("brc");

    args.named("no-libs");
    args.named("no-project-libs");
    args.named("no-env-libs");
    args.named("no-truncate");

    args.named("format").default("raw");
    args.named("dry-run").short('n');
    args.named("tree");
    args.named("with-symbols");
    args.named("help").short('h');
    args.raise_errors();

    if args.get("help").as_bool() {
        print_help(invocation);
        std::process::exit(0);
    }

    let source_path        = args.get("source").as_path_opt().map(
        |p| p.canonicalize().unwrap_or_else(|e| fatal!("{p:?}: {e:?}")));
    let destination_path   = args.get("destination").as_path_opt();
    let extension          = args.get("extension").as_string();
    let opt_extension      = Some(extension.as_str());

    let no_libs            = args.get("no-libs").as_bool();
    let no_project_libs    = args.get("no-project-libs").as_bool();
    let no_env_libs        = args.get("no-env-libs").as_bool();
    let no_truncate        = args.get("no-truncate").as_bool();

    let format             = Format::from_str(args.get("format").as_str());
    let dry_run            = args.get("dry-run").as_bool();
    let print_tree         = args.get("tree").as_bool();
    let export_symbols     = args.get("with-symbols").as_bool();

    // -----------------------------------------------------------------------

    let mut compiler = new_compiler();

    if let Some(path) = &source_path {
        info!("Reading program source from {path:?}");
        compiler.root_from_path(path).unwrap_or_else(|err| fatal!("{err:?}: {path:?}"));
    } else {
        let mut source_code = String::new();
        info!("Reading program source from standard input");
        if let Err(err) = std::io::stdin().read_to_string(&mut source_code) {
            fatal!("Could not read from standard input\n{err:?}");
        }
        compiler.root_from_string(source_code, "<standard input>")
    };
    if compiler.error().is_some() && !no_libs && !no_project_libs {
        compiler.include_libs_from_parent(opt_extension);
    }
    if compiler.error().is_some() && !no_libs && !no_env_libs {
        compiler.include_libs_from_path_variable("BEDROCK_LIBS", opt_extension);
    }

    if print_tree {
        compiler.hierarchy().report()
    }
    if let Some(error) = compiler.error() {
        error.report();
        std::process::exit(1);
    }

    let merged_source = compiler.get_compiled_source().unwrap_or_else(|error| {
        error.report();
        std::process::exit(1);
    });

    if !dry_run && format == Format::Source {
        write_bytes_and_exit(merged_source.as_bytes(), destination_path.as_ref());
    }

    // -----------------------------------------------------------------------

    let path = Some("<merged source>");
    let syntactic = match parse_syntactic(&merged_source, path) {
        Ok(tokens) => tokens,
        Err(errors) => {
            report_syntactic_errors(&errors, &merged_source);
            std::process::exit(1);
        }
    };

    let semantic = match parse_semantic(syntactic) {
        Ok(tokens) => tokens,
        Err(errors) => {
            report_semantic_errors(&errors, &merged_source);
            std::process::exit(1);
        }
    };

    let program = match generate_bytecode(&semantic) {
        Ok(program) => program,
        Err(errors) => {
            report_bytecode_errors(&errors, &merged_source);
            std::process::exit(1);
        }
    };

    let AssembledProgram { mut bytecode, symbols } = program;

    let length = bytecode.len();
    let percentage = (length as f32 / 65536.0 * 100.0).round() as u16;
    info!("Assembled program in {length} bytes ({percentage}% of maximum)");

    if !no_truncate {
        // Remove null bytes from end of bytecode.
        while let Some(0) = bytecode.last() {
            bytecode.pop();
        }
        let difference = length - bytecode.len();
        if difference > 0 {
            info!("Truncated program to {length} bytes (saved {difference} bytes)");
        }
    }

    if !dry_run {
        if export_symbols {
            if let Some(path) = &destination_path {
                let mut symbols_path = path.to_path_buf();
                symbols_path.add_extension("sym");
                let mut symbols_string = String::new();
                for symbol in &symbols {
                    let address = &symbol.address;
                    let name = &symbol.name;
                    let location = &symbol.source.location();
                    symbols_string.push_str(&format!(
                        "{address:04x} {name} {location}\n"
                    ));
                }
                match std::fs::write(&symbols_path, symbols_string) {
                    Ok(_) => info!("Saved symbols to {symbols_path:?}"),
                    Err(err) => info!("Could not write symbols to {symbols_path:?}\n{err:?}"),
                }
            }
        }

        let bytes = match format {
            Format::Raw => bytecode,
            Format::Clang => format_clang(&bytecode),
            Format::Source => unreachable!("Source output is handled before full assembly"),
        };
        write_bytes_and_exit(&bytes, destination_path.as_ref());
    }
}


fn write_bytes_and_exit<P: AsRef<Path>>(bytes: &[u8], path: Option<&P>) -> ! {
    match path {
        Some(path) => match std::fs::write(path, bytes) {
            Ok(_) => info!("Wrote output to {:?}", path.as_ref()),
            Err(err) => fatal!("Could not write to {:?}\n{err:?}", path.as_ref()),
        }
        None => match std::io::stdout().write_all(bytes) {
            Ok(_) => info!("Wrote output to standard output"),
            Err(err) => fatal!("Could not write to standard output\n{err:?}"),
        }
    }
    std::process::exit(0);
}


fn print_help(invocation: &str) {
    eprintln!("\
Usage: {invocation} [source] [destination]

Convert Bedrock source code into an assembled Bedrock program.

Usage:
  To assemble a Bedrock program from a source file and write to an output
  file, run `br-asm [source] [destination]`, where [source] is the path
  of the source file and [destination] is the path to write to.

  If [destination] is omitted, the assembled program will be written to
  standard output. If [source] is omitted, the program source code will
  be read from standard input.

Environment variables:
  BEDROCK_LIBS
    A list of colon-separated paths which will be searched to find Bedrock
    source code files to use as libraries when assembling a Bedrock program.
    If a library file resolves an unresolved symbol in the program being
    assembled, the library file will be merged into the program.

Arguments:
  [source]               Bedrock source code file to assemble.
  [destination]          Destination path for assembler output.

Switches:
  --dry-run        (-n)  Assemble and show errors only, don't write any output
  --extension=<ext>      File extension to identify source files (default is 'brc')
  --format=<fmt>         Output format to use for assembled program (default is 'raw')
  --no-project-libs      Don't search for libraries in the source parent folder
  --no-env-libs          Don't search for libraries in the BEDROCK_LIBS path variable
  --no-libs              Combination of --no-project-libs and --no-env-libs
  --no-truncate          Don't remove trailing zero-bytes from the assembled program
  --tree                 Show a tree diagram of all included library files
  --with-symbols         Also generate debug symbols file with extension '.sym'
  --help           (-h)  Print this help information
  --verbose,       (-v)  Print additional information
  --version              Print the program version and exit
");
}