nushell/src/prompt_update.rs

use nu_cli::NushellPrompt;
use nu_engine::eval_block;
use nu_protocol::{
    engine::{EngineState, Stack},
    Config, PipelineData, Span,
};
use reedline::Prompt;

// Name of environment variable where the prompt could be stored
pub(crate) const PROMPT_COMMAND: &str = "PROMPT_COMMAND";
pub(crate) const PROMPT_COMMAND_RIGHT: &str = "PROMPT_COMMAND_RIGHT";
pub(crate) const PROMPT_INDICATOR: &str = "PROMPT_INDICATOR";
pub(crate) const PROMPT_INDICATOR_VI_INSERT: &str = "PROMPT_INDICATOR_VI_INSERT";
pub(crate) const PROMPT_INDICATOR_VI_VISUAL: &str = "PROMPT_INDICATOR_VI_VISUAL";
pub(crate) const PROMPT_MULTILINE_INDICATOR: &str = "PROMPT_MULTILINE_INDICATOR";

pub(crate) fn get_prompt_indicators(
    config: &Config,
    engine_state: &EngineState,
    stack: &Stack,
) -> (String, String, String, String) {
    let prompt_indicator = match stack.get_env_var(engine_state, PROMPT_INDICATOR) {
        Some(pi) => pi.into_string("", config),
        None => "〉".to_string(),
    };

    let prompt_vi_insert = match stack.get_env_var(engine_state, PROMPT_INDICATOR_VI_INSERT) {
        Some(pvii) => pvii.into_string("", config),
        None => ": ".to_string(),
    };

    let prompt_vi_visual = match stack.get_env_var(engine_state, PROMPT_INDICATOR_VI_VISUAL) {
        Some(pviv) => pviv.into_string("", config),
        None => "v ".to_string(),
    };

    let prompt_multiline = match stack.get_env_var(engine_state, PROMPT_MULTILINE_INDICATOR) {
        Some(pm) => pm.into_string("", config),
        None => "::: ".to_string(),
    };

    (
        prompt_indicator,
        prompt_vi_insert,
        prompt_vi_visual,
        prompt_multiline,
    )
}

fn get_prompt_string(
    prompt: &str,
    config: &Config,
    engine_state: &EngineState,
    stack: &mut Stack,
) -> Option<String> {
    stack
        .get_env_var(engine_state, prompt)
        .and_then(|v| v.as_block().ok())
        .and_then(|block_id| {
            let block = engine_state.get_block(block_id);
            eval_block(
                engine_state,
                stack,
                block,
                PipelineData::new(Span::new(0, 0)), // Don't try this at home, 0 span is ignored
            )
            .ok()
        })
        .and_then(|pipeline_data| pipeline_data.collect_string("", config).ok())
}

pub(crate) fn update_prompt<'prompt>(
    config: &Config,
    engine_state: &EngineState,
    stack: &Stack,
    nu_prompt: &'prompt mut NushellPrompt,
) -> &'prompt dyn Prompt {
    // get the other indicators
    let (
        prompt_indicator_string,
        prompt_vi_insert_string,
        prompt_vi_visual_string,
        prompt_multiline_string,
    ) = get_prompt_indicators(config, engine_state, stack);

    let mut stack = stack.clone();

    // apply the other indicators
    nu_prompt.update_all_prompt_strings(
        get_prompt_string(PROMPT_COMMAND, config, engine_state, &mut stack),
        get_prompt_string(PROMPT_COMMAND_RIGHT, config, engine_state, &mut stack),
        prompt_indicator_string,
        prompt_vi_insert_string,
        prompt_vi_visual_string,
        prompt_multiline_string,
    );

    nu_prompt as &dyn Prompt
}