extern crate handlebars;

use crate::data::{ExternalEvent, LINE_SPACE};
use handlebars::Handlebars;
use std::{cmp::max, collections::BTreeMap};
use std::fs::File;
use std::io;

pub fn render_code_panel(
    annotated_lines: io::Lines<io::BufReader<File>>,
    lines: io::Lines<io::BufReader<File>>,
    max_x_space: &mut i64,
    event_line_map: &BTreeMap<usize, Vec<ExternalEvent>>,
) -> (String, i32) {
    /* Template creation */
    let mut handlebars = Handlebars::new();
    // We want to preserve the inputs `as is`, and want to make no changes based on html escape.
    handlebars.register_escape_fn(handlebars::no_escape);
    let line_template =
        "        <text class=\"code\" x=\"{{X_VAL}}\" y=\"{{Y_VAL}}\"> {{LINE}} </text>\n";
    // register the template. The template string will be verified and compiled.
    assert!(handlebars
        .register_template_string("code_line_template", line_template)
        .is_ok());
    
    // figure out that max length
    for line in lines {
        if let Ok(line_string) = line {
            *max_x_space = max(line_string.len() as i64, *max_x_space);
        }
    }
    
    /* Render the code segment of the svg to a String */
    let x = 20;
    let mut y = 90;
    let mut output = String::from("    <g id=\"code\">\n");
    let mut line_of_code = 1;
    for line in annotated_lines {
        if let Ok(line_string) = line {
            let mut data = BTreeMap::new();
            data.insert("X_VAL".to_string(), x.to_string());
            data.insert("Y_VAL".to_string(), y.to_string());
            /* automatically add line numbers to code */
            let fmt_line = format!(
                "<tspan fill=\"#AAA\">{}  </tspan>{}",
                line_of_code, line_string
            );
            data.insert("LINE".to_string(), fmt_line);
            output.push_str(&handlebars.render("code_line_template", &data).unwrap());
            // change line spacing
            y = y + LINE_SPACE;
        }
        let mut extra_line_num = 0;
        match event_line_map.get(&(line_of_code as usize)) {
            Some(event_vec) => extra_line_num = event_vec.len(),
            None => (),
        }
        /* add empty lines for arrows */
        while extra_line_num > 1 {
            let mut data = BTreeMap::new();
            data.insert("X_VAL".to_string(), x.to_string());
            data.insert("Y_VAL".to_string(), y.to_string());
            /* automatically add line numbers to code */
            line_of_code = line_of_code + 1;
            let empty_line = format!("<tspan fill=\"#AAA\">{}</tspan>", line_of_code);
            data.insert("LINE".to_string(), empty_line);
            output.push_str(&handlebars.render("code_line_template", &data).unwrap());
            y = y + LINE_SPACE;
            extra_line_num -= 1;
        }
        line_of_code = line_of_code + 1;
    }
    output.push_str("    </g>\n");
    (output, line_of_code)
}