use super::*;

use anyhow::{bail, Result};
use async_recursion::async_recursion;
use lazy_static::lazy_static;
use std::{fs::read_to_string, path::Path};
use which::which;

lazy_static! {
    static ref EXIST_PANDOC: bool = which("pandoc").is_ok();
    static ref EXIST_PDFTOTEXT: bool = which("pdftotext").is_ok();
}

pub fn load(path: &str, extension: &str) -> Result<Vec<RagDocument>> {
    match extension {
        "docx" | "epub" => load_with_pandoc(path),
        "pdf" => load_with_pdftotext(path),
        _ => load_plain(path),
    }
}

fn load_plain(path: &str) -> Result<Vec<RagDocument>> {
    let contents = read_to_string(path)?;
    let document = RagDocument::new(contents);
    Ok(vec![document])
}

fn load_with_pdftotext(path: &str) -> Result<Vec<RagDocument>> {
    if !*EXIST_PDFTOTEXT {
        bail!("Need to install pdftotext (part of the poppler package) to load the file.")
    }
    let contents = run_external_tool("pdftotext", &[path, "-"])?;
    let document = RagDocument::new(contents);
    Ok(vec![document])
}

fn load_with_pandoc(path: &str) -> Result<Vec<RagDocument>> {
    if !*EXIST_PANDOC {
        bail!("Need to install pandoc to load the file.")
    }
    let contents = run_external_tool("pandoc", &["--to", "plain", path])?;
    let document = RagDocument::new(contents);
    Ok(vec![document])
}

pub fn parse_glob(path_str: &str) -> Result<(String, Vec<String>)> {
    if let Some(start) = path_str.find("/**/*.").or_else(|| path_str.find(r"\**\*.")) {
        let base_path = path_str[..start].to_string();
        if let Some(curly_brace_end) = path_str[start..].find('}') {
            let end = start + curly_brace_end;
            let extensions_str = &path_str[start + 6..end + 1];
            let extensions = if extensions_str.starts_with('{') && extensions_str.ends_with('}') {
                extensions_str[1..extensions_str.len() - 1]
                    .split(',')
                    .map(|s| s.to_string())
                    .collect::<Vec<String>>()
            } else {
                bail!("Invalid path '{path_str}'");
            };
            Ok((base_path, extensions))
        } else {
            let extensions_str = &path_str[start + 6..];
            let extensions = vec![extensions_str.to_string()];
            Ok((base_path, extensions))
        }
    } else {
        Ok((path_str.to_string(), vec![]))
    }
}

#[async_recursion]
pub async fn list_files(
    files: &mut Vec<String>,
    entry_path: &Path,
    suffixes: Option<&Vec<String>>,
) -> Result<()> {
    if !entry_path.exists() {
        bail!("Not found: {:?}", entry_path);
    }
    if entry_path.is_file() {
        add_file(files, suffixes, entry_path);
        return Ok(());
    }
    if !entry_path.is_dir() {
        bail!("Not a directory: {:?}", entry_path);
    }
    let mut reader = tokio::fs::read_dir(entry_path).await?;
    while let Some(entry) = reader.next_entry().await? {
        let path = entry.path();
        if path.is_file() {
            add_file(files, suffixes, &path);
        } else if path.is_dir() {
            list_files(files, &path, suffixes).await?;
        }
    }
    Ok(())
}

fn add_file(files: &mut Vec<String>, suffixes: Option<&Vec<String>>, path: &Path) {
    if is_valid_extension(suffixes, path) {
        files.push(path.display().to_string());
    }
}

fn is_valid_extension(suffixes: Option<&Vec<String>>, path: &Path) -> bool {
    if let Some(suffixes) = suffixes {
        if !suffixes.is_empty() {
            if let Some(extension) = path.extension().map(|v| v.to_string_lossy().to_string()) {
                return suffixes.contains(&extension);
            }
            return false;
        }
    }
    true
}

fn run_external_tool(cmd: &str, args: &[&str]) -> Result<String> {
    let (success, stdout, stderr) = run_command_with_output(cmd, args, None)?;
    if success {
        return Ok(stdout);
    }
    let err = if !stderr.is_empty() {
        stderr
    } else {
        format!("`{cmd}` exited with non-zero.")
    };
    bail!("{err}")
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_parse_glob() {
        assert_eq!(parse_glob("dir").unwrap(), ("dir".into(), vec![]));
        assert_eq!(
            parse_glob("dir/file.md").unwrap(),
            ("dir/file.md".into(), vec![])
        );
        assert_eq!(
            parse_glob("dir/**/*.md").unwrap(),
            ("dir".into(), vec!["md".into()])
        );
        assert_eq!(
            parse_glob("dir/**/*.{md,txt}").unwrap(),
            ("dir".into(), vec!["md".into(), "txt".into()])
        );
        assert_eq!(
            parse_glob("C:\\dir\\**\\*.{md,txt}").unwrap(),
            ("C:\\dir".into(), vec!["md".into(), "txt".into()])
        );
    }
}