// Copyright (C) 2022 Bauke <me@bauke.xyz>
//
// This program is free software: you can redistribute it and/or modify it under
// the terms of the GNU Affero General Public License as published by the Free
// Software Foundation, either version 3 of the License, or (at your option) any
// later version.
//
// This program is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
// FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
// details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.

//! # Select HTML
//!
//! > **Extract HTML using CSS selectors in the command-line.**

#![forbid(unsafe_code)]
#![warn(missing_docs, clippy::missing_docs_in_private_items)]

use std::{
  fs::File,
  io::{stdin, Read},
  path::PathBuf,
};

use {
  clap::Parser,
  color_eyre::{eyre::eyre, install, Result},
  scraper::{Html, Selector},
};

/// CLI arguments struct using [`clap`]'s Derive API.
#[derive(Debug, Parser)]
#[clap(about, author, version)]
pub struct Args {
  /// Output the attribute's value from the selected element, can be used
  /// multiple times.
  #[clap(short, long, group = "output")]
  pub attribute: Vec<String>,

  /// A HTML file to read, if not specified stdin will be used instead.
  #[clap(long, parse(from_os_str))]
  pub file: Option<PathBuf>,

  /// The CSS selector to use.
  pub selector: String,

  /// Output inner text of the selected elements.
  #[clap(short, long, group = "output")]
  pub text: bool,

  /// Trim whitespace from selected items.
  #[clap(long)]
  pub trim: bool,
}

/// The main CLI function.
fn main() -> Result<()> {
  install()?;

  let args = Args::parse();

  let selector = Selector::parse(&args.selector)
    .map_err(|_| eyre!("Failed to parse selector"))?;

  let document = {
    let mut html = String::new();

    if let Some(path) = args.file {
      File::open(path)?.read_to_string(&mut html)?;
    } else {
      stdin().read_to_string(&mut html)?;
    };

    Html::parse_document(&html)
  };

  let mut to_print = vec![];

  for element in document.select(&selector) {
    if args.text {
      to_print.push(element.text().collect::<String>());
    } else if !args.attribute.is_empty() {
      let element = element.value();
      for attribute in &args.attribute {
        if let Some(value) = element.attr(attribute) {
          to_print.push(value.to_string());
        }
      }
    } else {
      to_print.push(element.html());
    }
  }

  for value in to_print {
    if args.trim {
      println!("{}", value.trim());
    } else {
      println!("{}", value);
    }
  }

  Ok(())
}