use crate::line_editor::configure_ctrl_c;
use nu_command::commands::default_context::create_default_context;
#[allow(unused_imports)]
use nu_command::maybe_print_errors;
use nu_engine::run_block;
use nu_engine::EvaluationContext;

#[allow(unused_imports)]
pub(crate) use nu_command::script::{process_script, LineResult};

#[cfg(feature = "rustyline-support")]
use crate::line_editor::{
    configure_rustyline_editor, convert_rustyline_result_to_string,
    default_rustyline_editor_configuration, nu_line_editor_helper,
};

#[allow(unused_imports)]
use nu_data::config;
use nu_source::{Tag, Text};
use nu_stream::InputStream;
#[allow(unused_imports)]
use std::sync::atomic::Ordering;

use nu_command::script::{print_err, run_script_standalone};

#[cfg(feature = "rustyline-support")]
use rustyline::{self, error::ReadlineError};

use crate::EnvironmentSyncer;
use nu_errors::ShellError;
use nu_parser::ParserScope;
use nu_protocol::{hir::ExternalRedirection, UntaggedValue, Value};

use std::error::Error;
use std::iter::Iterator;
use std::path::PathBuf;

pub fn search_paths() -> Vec<std::path::PathBuf> {
    use std::env;

    let mut search_paths = Vec::new();

    // Automatically add path `nu` is in as a search path
    if let Ok(exe_path) = env::current_exe() {
        if let Some(exe_dir) = exe_path.parent() {
            search_paths.push(exe_dir.to_path_buf());
        }
    }

    if let Ok(config) = nu_data::config::config(Tag::unknown()) {
        if let Some(Value {
            value: UntaggedValue::Table(pipelines),
            ..
        }) = config.get("plugin_dirs")
        {
            for pipeline in pipelines {
                if let Ok(plugin_dir) = pipeline.as_string() {
                    search_paths.push(PathBuf::from(plugin_dir));
                }
            }
        }
    }

    search_paths
}

pub async fn run_script_file(
    file_contents: String,
    redirect_stdin: bool,
) -> Result<(), Box<dyn Error>> {
    let mut syncer = EnvironmentSyncer::new();
    let mut context = create_default_context(false)?;
    let config = syncer.get_config();

    context.configure(&config, |_, ctx| {
        syncer.load_environment();
        syncer.sync_env_vars(ctx);
        syncer.sync_path_vars(ctx);

        if let Err(reason) = syncer.autoenv(ctx) {
            print_err(reason, &Text::from(""));
        }

        let _ = register_plugins(ctx);
        let _ = configure_ctrl_c(ctx);
    });

    let _ = run_startup_commands(&mut context, &config).await;

    run_script_standalone(file_contents, redirect_stdin, &context, true).await?;

    Ok(())
}

/// The entry point for the CLI. Will register all known internal commands, load experimental commands, load plugins, then prepare the prompt and line reader for input.
#[cfg(feature = "rustyline-support")]
pub async fn cli(mut context: EvaluationContext) -> Result<(), Box<dyn Error>> {
    let mut syncer = EnvironmentSyncer::new();
    let configuration = syncer.get_config();

    let mut rl = default_rustyline_editor_configuration();

    context.configure(&configuration, |config, ctx| {
        syncer.load_environment();
        syncer.sync_env_vars(ctx);
        syncer.sync_path_vars(ctx);

        if let Err(reason) = syncer.autoenv(ctx) {
            print_err(reason, &Text::from(""));
        }

        let _ = configure_ctrl_c(ctx);
        let _ = configure_rustyline_editor(&mut rl, config);

        let helper = Some(nu_line_editor_helper(ctx, config));
        rl.set_helper(helper);
    });

    let _ = run_startup_commands(&mut context, &configuration).await;

    // Give ourselves a scope to work in
    context.scope.enter_scope();

    let history_path = nu_engine::history_path(&configuration);
    let _ = rl.load_history(&history_path);

    let mut session_text = String::new();
    let mut line_start: usize = 0;

    let skip_welcome_message = configuration
        .var("skip_welcome_message")
        .map(|x| x.is_true())
        .unwrap_or(false);
    if !skip_welcome_message {
        println!(
            "Welcome to Nushell {} (type 'help' for more info)",
            clap::crate_version!()
        );
    }

    #[cfg(windows)]
    {
        let _ = ansi_term::enable_ansi_support();
    }

    let mut ctrlcbreak = false;

    loop {
        if context.ctrl_c.load(Ordering::SeqCst) {
            context.ctrl_c.store(false, Ordering::SeqCst);
            continue;
        }

        let cwd = context.shell_manager.path();

        let colored_prompt = {
            if let Some(prompt) = configuration.var("prompt") {
                let prompt_line = prompt.as_string()?;

                context.scope.enter_scope();
                let (mut prompt_block, err) = nu_parser::parse(&prompt_line, 0, &context.scope);

                prompt_block.set_redirect(ExternalRedirection::Stdout);

                if err.is_some() {
                    context.scope.exit_scope();

                    format!("\x1b[32m{}{}\x1b[m> ", cwd, current_branch())
                } else {
                    // let env = context.get_env();

                    let run_result = run_block(&prompt_block, &context, InputStream::empty()).await;
                    context.scope.exit_scope();

                    match run_result {
                        Ok(result) => match result.collect_string(Tag::unknown()).await {
                            Ok(string_result) => {
                                let errors = context.get_errors();
                                maybe_print_errors(&context, Text::from(prompt_line));
                                context.clear_errors();

                                if !errors.is_empty() {
                                    "> ".to_string()
                                } else {
                                    string_result.item
                                }
                            }
                            Err(e) => {
                                crate::cli::print_err(e, &Text::from(prompt_line));
                                context.clear_errors();

                                "> ".to_string()
                            }
                        },
                        Err(e) => {
                            crate::cli::print_err(e, &Text::from(prompt_line));
                            context.clear_errors();

                            "> ".to_string()
                        }
                    }
                }
            } else {
                format!("\x1b[32m{}{}\x1b[m> ", cwd, current_branch())
            }
        };

        let prompt = {
            if let Ok(bytes) = strip_ansi_escapes::strip(&colored_prompt) {
                String::from_utf8_lossy(&bytes).to_string()
            } else {
                "> ".to_string()
            }
        };

        rl.helper_mut().expect("No helper").colored_prompt = colored_prompt;
        let mut initial_command = Some(String::new());
        let mut readline = Err(ReadlineError::Eof);
        while let Some(ref cmd) = initial_command {
            readline = rl.readline_with_initial(&prompt, (&cmd, ""));
            initial_command = None;
        }

        if let Ok(line) = &readline {
            line_start = session_text.len();
            session_text.push_str(line);
            session_text.push('\n');
        }

        let line = match convert_rustyline_result_to_string(readline) {
            LineResult::Success(_) => {
                process_script(
                    &session_text[line_start..],
                    &context,
                    false,
                    line_start,
                    true,
                )
                .await
            }
            x => x,
        };

        // Check the config to see if we need to update the path
        // TODO: make sure config is cached so we don't path this load every call
        // FIXME: we probably want to be a bit more graceful if we can't set the environment

        context.configure(&configuration, |config, ctx| {
            if syncer.did_config_change() {
                syncer.reload();
                syncer.sync_env_vars(ctx);
                syncer.sync_path_vars(ctx);
            }

            if let Err(reason) = syncer.autoenv(ctx) {
                print_err(reason, &Text::from(""));
            }

            let _ = configure_rustyline_editor(&mut rl, config);
        });

        match line {
            LineResult::Success(line) => {
                rl.add_history_entry(&line);
                let _ = rl.save_history(&history_path);
                maybe_print_errors(&context, Text::from(session_text.clone()));
            }

            LineResult::ClearHistory => {
                rl.clear_history();
                let _ = rl.save_history(&history_path);
            }

            LineResult::Error(line, err) => {
                rl.add_history_entry(&line);
                let _ = rl.save_history(&history_path);

                context.with_host(|_host| {
                    print_err(err, &Text::from(session_text.clone()));
                });

                maybe_print_errors(&context, Text::from(session_text.clone()));
            }

            LineResult::CtrlC => {
                let config_ctrlc_exit = config::config(Tag::unknown())?
                    .get("ctrlc_exit")
                    .map(|s| s.value.is_true())
                    .unwrap_or(false); // default behavior is to allow CTRL-C spamming similar to other shells

                if !config_ctrlc_exit {
                    continue;
                }

                if ctrlcbreak {
                    let _ = rl.save_history(&history_path);
                    std::process::exit(0);
                } else {
                    context.with_host(|host| host.stdout("CTRL-C pressed (again to quit)"));
                    ctrlcbreak = true;
                    continue;
                }
            }

            LineResult::CtrlD => {
                context.shell_manager.remove_at_current();
                if context.shell_manager.is_empty() {
                    break;
                }
            }

            LineResult::Break => {
                break;
            }
        }
        ctrlcbreak = false;
    }

    // we are ok if we can not save history
    let _ = rl.save_history(&history_path);

    Ok(())
}

pub fn register_plugins(context: &mut EvaluationContext) -> Result<(), ShellError> {
    if let Ok(plugins) = nu_engine::plugin::build_plugin::scan(search_paths()) {
        context.add_commands(
            plugins
                .into_iter()
                .filter(|p| !context.is_command_registered(p.name()))
                .collect(),
        );
    }

    Ok(())
}

async fn run_startup_commands(
    context: &mut EvaluationContext,
    config: &dyn nu_data::config::Conf,
) -> Result<(), ShellError> {
    if let Some(commands) = config.var("startup") {
        match commands {
            Value {
                value: UntaggedValue::Table(pipelines),
                ..
            } => {
                let mut script_file = String::new();
                for pipeline in pipelines {
                    script_file.push_str(&pipeline.as_string()?);
                    script_file.push('\n');
                }
                let _ = run_script_standalone(script_file, false, context, false).await;
            }
            _ => {
                return Err(ShellError::untagged_runtime_error(
                    "expected a table of pipeline strings as startup commands",
                ));
            }
        }
    }

    Ok(())
}

pub async fn parse_and_eval(line: &str, ctx: &EvaluationContext) -> Result<String, ShellError> {
    // FIXME: do we still need this?
    let line = if let Some(s) = line.strip_suffix('\n') {
        s
    } else {
        line
    };

    // TODO ensure the command whose examples we're testing is actually in the pipeline
    ctx.scope.enter_scope();
    let (classified_block, err) = nu_parser::parse(&line, 0, &ctx.scope);
    if let Some(err) = err {
        ctx.scope.exit_scope();
        return Err(err.into());
    }

    let input_stream = InputStream::empty();
    let env = ctx.get_env();
    ctx.scope.add_env(env);

    let result = run_block(&classified_block, ctx, input_stream).await;
    ctx.scope.exit_scope();

    result?.collect_string(Tag::unknown()).await.map(|x| x.item)
}

#[allow(dead_code)]
fn current_branch() -> String {
    #[cfg(feature = "shadow-rs")]
    {
        Some(shadow_rs::branch())
            .map(|x| x.trim().to_string())
            .filter(|x| !x.is_empty())
            .map(|x| format!("({})", x))
            .unwrap_or_default()
    }
    #[cfg(not(feature = "shadow-rs"))]
    {
        "".to_string()
    }
}

#[cfg(test)]
mod tests {
    use nu_engine::basic_evaluation_context;

    #[quickcheck]
    fn quickcheck_parse(data: String) -> bool {
        let (tokens, err) = nu_parser::lex(&data, 0);
        let (lite_block, err2) = nu_parser::parse_block(tokens);
        if err.is_none() && err2.is_none() {
            let context = basic_evaluation_context().unwrap();
            let _ = nu_parser::classify_block(&lite_block, &context.scope);
        }
        true
    }
}