//! The module that implements the `wasmtime wast` command.

use clap::Parser;
use std::path::PathBuf;
use wasmtime::{Engine, Result, error::Context as _};
use wasmtime_cli_flags::CommonOptions;
use wasmtime_wast::{SpectestConfig, WastContext};

/// Runs a WebAssembly test script file
#[derive(Parser)]
pub struct WastCommand {
    #[command(flatten)]
    common: CommonOptions,

    /// The path of the WebAssembly test script to run
    #[arg(required = true, value_name = "SCRIPT_FILE")]
    scripts: Vec<PathBuf>,

    /// Whether or not to generate DWARF debugging information in text-to-binary
    /// transformations to show line numbers in backtraces.
    #[arg(long, require_equals = true, value_name = "true|false")]
    generate_dwarf: Option<Option<bool>>,

    /// Saves precompiled versions of modules to this path instead of running
    /// tests.
    #[arg(long)]
    precompile_save: Option<PathBuf>,

    /// Load precompiled modules from the specified directory instead of
    /// compiling natively.
    #[arg(long)]
    precompile_load: Option<PathBuf>,

    /// Whether or not to run wasm in async mode.
    ///
    /// This is enabled by default but disabling it may be useful when testing
    /// Wasmtime itself.
    #[arg(long = "async", require_equals = true, value_name = "true|false")]
    async_: Option<Option<bool>>,

    /// Whether or not to enable wasmtime's builtin functions for the `*.wast`
    /// to import.
    #[arg(long = "wasmtime-builtins")]
    wasmtime_builtins: bool,
}

impl WastCommand {
    /// Executes the command.
    pub fn execute(mut self) -> Result<()> {
        self.common.init_logging()?;

        let async_ = optional_flag_with_default(self.async_, true);
        let mut config = self.common.config(None)?;
        config.shared_memory(true);
        let engine = Engine::new(&config)?;
        let mut wast_context = WastContext::new(
            &engine,
            if async_ {
                wasmtime_wast::Async::Yes
            } else {
                wasmtime_wast::Async::No
            },
            move |store| {
                if let Some(fuel) = self.common.wasm.fuel {
                    store.set_fuel(fuel).unwrap();
                }
                if let Some(true) = self.common.wasm.epoch_interruption {
                    store.epoch_deadline_trap();
                    store.set_epoch_deadline(1);
                }
            },
        );

        wast_context.generate_dwarf(optional_flag_with_default(self.generate_dwarf, true));
        wast_context
            .register_spectest(&SpectestConfig {
                use_shared_memory: true,
                suppress_prints: false,
            })
            .expect("error instantiating \"spectest\"");

        if let Some(path) = &self.precompile_save {
            wast_context.precompile_save(path);
        }
        if let Some(path) = &self.precompile_load {
            wast_context.precompile_load(path);
        }

        if self.wasmtime_builtins {
            wast_context.register_wasmtime()?;
        }

        for script in self.scripts.iter() {
            wast_context
                .run_file(script)
                .with_context(|| format!("failed to run script file '{}'", script.display()))?;
        }

        Ok(())
    }
}

fn optional_flag_with_default(flag: Option<Option<bool>>, default: bool) -> bool {
    match flag {
        None => default,
        Some(None) => true,
        Some(Some(val)) => val,
    }
}
