use std::{ffi::OsStr, fs, path::Path};

use codemap::Spanned;
use peekmore::PeekMore;

use crate::{common::QuoteKind, error::SassResult, lexer::Lexer, value::Value, Token};

use super::{Parser, Stmt};

impl<'a> Parser<'a> {
    pub(super) fn import(&mut self) -> SassResult<Vec<Stmt>> {
        self.whitespace();

        match self.toks.peek() {
            Some(Token { kind: '\'', .. })
            | Some(Token { kind: '"', .. })
            | Some(Token { kind: 'u', .. }) => {}
            Some(Token { pos, .. }) => return Err(("Expected string.", *pos).into()),
            None => return Err(("expected more input.", self.span_before).into()),
        };

        let Spanned {
            node: file_name_as_value,
            span,
        } = self.parse_value()?;
        let file_name = match file_name_as_value {
            Value::String(s, QuoteKind::Quoted) => {
                if s.ends_with(".css") || s.starts_with("http://") || s.starts_with("https://") {
                    return Ok(vec![Stmt::Import(format!("\"{}\"", s))]);
                } else {
                    s
                }
            }
            Value::String(s, QuoteKind::None) => {
                if s.starts_with("url(") {
                    return Ok(vec![Stmt::Import(s)]);
                } else {
                    s
                }
            }
            _ => return Err(("Expected string.", span).into()),
        };

        self.whitespace();

        let path: &Path = file_name.as_ref();

        let path_buf = if path.is_absolute() {
            // todo: test for absolute path imports
            path.into()
        } else {
            self.path
                .parent()
                .unwrap_or_else(|| Path::new(""))
                .join(path)
        };

        let name = path_buf.file_name().unwrap_or_else(|| OsStr::new(".."));

        let paths = [
            path_buf.with_file_name(name).with_extension("scss"),
            path_buf
                .with_file_name(format!("_{}", name.to_str().unwrap()))
                .with_extension("scss"),
            path_buf.clone(),
            path_buf.join("index.scss"),
            path_buf.join("_index.scss"),
        ];

        for name in &paths {
            if name.is_file() {
                let file = self.map.add_file(
                    name.to_string_lossy().into(),
                    String::from_utf8(fs::read(name)?)?,
                );

                return Parser {
                    toks: &mut Lexer::new(&file)
                        .collect::<Vec<Token>>()
                        .into_iter()
                        .peekmore(),
                    map: self.map,
                    path: name.as_ref(),
                    scopes: self.scopes,
                    global_scope: self.global_scope,
                    super_selectors: self.super_selectors,
                    span_before: file.span.subspan(0, 0),
                    content: self.content,
                    flags: self.flags,
                    at_root: self.at_root,
                    at_root_has_selector: self.at_root_has_selector,
                    extender: self.extender,
                    content_scopes: self.content_scopes,
                }
                .parse();
            }
        }

        Err(("Can't find stylesheet to import.", span).into())
    }
}