//! This module is only used when the feature `terminfo` is not activated.

use proc_macro::TokenStream;
use proc_macro2::TokenStream as TokenStream2;
use quote::{quote, ToTokens};

use crate::color_context::Context;
use crate::error::{SpanError, Error};
use crate::format_args::{
    parse_args, get_format_string, get_args_and_format_string, parse_format_string, Node
};

/// Common code shared between the three public macros, ANSI implementation.
pub fn get_format_args(input: TokenStream) -> Result<TokenStream2, SpanError> {
    let (format_string_token, args) = get_args_and_format_string(input)?;
    let format_string = format_string_token.value();

    // Split the format string into a list of nodes; each node is either a string literal (text), a
    // placeholder for a `format!`-like macro, or a color code:
    let format_nodes = parse_format_string(&format_string, &format_string_token)?;

    let final_format_string = get_format_string_from_nodes(format_nodes)?;

    // Group all the final arguments into a single iterator:
    let args = args.iter()
        .map(|arg| arg.to_token_stream())
        .skip(1); // Skip the original format string
    let final_args = std::iter::once(final_format_string).chain(args);

    Ok(quote! { #(#final_args),* })
}

/// Transforms a string literal by parsing its color tags.
pub fn get_cstr(input: TokenStream) -> Result<TokenStream2, SpanError> {
    let args = parse_args(input)?;
    let format_string_token = get_format_string(args.first())?;
    let format_string = format_string_token.value();

    if args.len() > 1 {
        return Err(SpanError::new(Error::TooManyArgs, None));
    }

    // Split the format string into a list of nodes; each node is either a string literal (text),
    // or a color code; `format!`-like placeholders will be parsed indenpendently, but as they are
    // put back unchanged into the format string, it's not a problem:
    let format_nodes = parse_format_string(&format_string, &format_string_token)?;
    get_format_string_from_nodes(format_nodes)
}

/// Generates a new format string with the color tags replaced by the right ANSI codes.
fn get_format_string_from_nodes(nodes: Vec<Node>) -> Result<TokenStream2, SpanError> {
    // The final, modified format string which will be given to the `format!`-like macro:
    let mut format_string = String::new();
    // Stores which colors and attributes are set while processing the format string:
    let mut color_context = Context::new();

    // Generate the final format string:
    for node in nodes {
        match node {
            Node::Text(s) | Node::Placeholder(s) => {
                format_string.push_str(s);
            }
            Node::ColorTagGroup(tag_group) => {
                let ansi_string = color_context.ansi_apply_tags(tag_group)?;
                format_string.push_str(&ansi_string);
            }
        }
    }

    Ok(quote! { #format_string })
}