use std::path::PathBuf;

use embed_nu::{Argument, CommandGroupConfig, Context, ValueIntoExpression};
use tokio::fs;

use crate::{
    distro::OSConfig,
    error::{AppError, AppResult},
};

pub struct ExecBuilder {
    pub script: PathBuf,
    pub os_config: OSConfig,
    pub task_config: embed_nu::Value,
}

impl ExecBuilder {
    pub async fn exec(self) -> AppResult<()> {
        let script_contents = self.get_script_contents().await?;
        let mut ctx = Context::builder()
            .with_command_groups(CommandGroupConfig::default().all_groups(true))?
            .add_var("TRM_CONFIG", self.os_config)?
            .add_script(script_contents)?
            .build()?;
        if ctx.has_fn("main") {
            let pipeline = ctx.call_fn(
                "main",
                vec![Argument::Positional(self.task_config.into_expression())],
            )?;
            ctx.print_pipeline_stderr(pipeline)?;

            Ok(())
        } else {
            Err(AppError::MissingMain(self.script))
        }
    }

    async fn get_script_contents(&self) -> AppResult<String> {
        let contents = fs::read_to_string(&self.script).await?;

        Ok(contents)
    }
}