#![warn(clippy::all, clippy::pedantic)]

use crate::converter::html_to_markdown;
use crate::doc_processor::{DocProcessResult, try_convert};
use crate::error_logger::log_error;
use crate::extractor::extract_links;
use crate::fetcher::{FetchResult, Fetcher};
use crate::robots::RobotsRule;
use crate::url_utils::{get_extension, is_in_scope, normalize_url, url_to_filename};
use anyhow::Result;
use std::collections::{HashSet, VecDeque};
use std::fs;
use std::time::Duration;
use url::Url;

const DOC_TYPES: &[&str] = &[
    "application/pdf",
    "application/msword",
    "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
    "application/vnd.ms-word.document.macroenabled.12",
    "application/vnd.ms-powerpoint",
    "application/vnd.openxmlformats-officedocument.presentationml.presentation",
    "application/vnd.ms-powerpoint.presentation.macroenabled.12",
    "application/vnd.ms-excel",
    "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
    "application/vnd.ms-excel.sheet.macroenabled.12",
    "application/vnd.ms-excel.sheet.binary.macroenabled.12",
    "application/vnd.oasis.opendocument.text",
    "application/vnd.oasis.opendocument.spreadsheet",
    "application/vnd.oasis.opendocument.presentation",
    "application/rtf",
    "application/epub+zip",
    "text/csv",
];

#[derive(Default)]
pub struct DocStats {
    pub converted: usize,
    pub raw: usize,
    pub errors: usize,
}

pub struct Scraper {
    fetcher: Fetcher,
    seen: HashSet<String>,
    output_dir: std::path::PathBuf,
    log_path: std::path::PathBuf,
    base_host: String,
    robots: RobotsRule,
    doc_stats: DocStats,
    convert_docs: bool,
    include_types: Option<HashSet<String>>,
    exclude_types: Option<HashSet<String>>,
    scope_path: Option<String>,
    single_page: bool,
    allow_subdomains: bool,
    delay_ms: u64,
}

impl Scraper {
    #[allow(clippy::too_many_arguments)]
    pub fn new(
        output_dir: std::path::PathBuf,
        log_path: std::path::PathBuf,
        base_host: String,
        robots: RobotsRule,
        convert_docs: bool,
        fetcher: Fetcher,
        include_types: Option<HashSet<String>>,
        exclude_types: Option<HashSet<String>>,
        scope_path: Option<String>,
        single_page: bool,
        allow_subdomains: bool,
        delay_ms: u64,
    ) -> Self {
        Self {
            fetcher,
            seen: HashSet::new(),
            output_dir,
            log_path,
            base_host,
            robots,
            doc_stats: DocStats::default(),
            convert_docs,
            include_types,
            exclude_types,
            scope_path,
            single_page,
            allow_subdomains,
            delay_ms,
        }
    }

    fn should_save(&self, url: &Url, content_type: &str) -> (bool, String) {
        let ext = get_extension(url, content_type);
        let ext_clean = ext.trim_start_matches('.').to_lowercase();

        if let Some(include) = &self.include_types {
            if include.contains(&ext_clean) {
                (true, ext_clean)
            } else {
                (false, ext_clean)
            }
        } else if let Some(exclude) = &self.exclude_types {
            if exclude.contains(&ext_clean) {
                (false, ext_clean)
            } else {
                (true, ext_clean)
            }
        } else {
            (true, ext_clean)
        }
    }

    fn extract_new_links(&self, html: &str, final_url: &Url) -> (usize, Vec<Url>) {
        let links = extract_links(html, final_url, &self.base_host, self.allow_subdomains);
        let new_count = links.len();
        let new_links: Vec<Url> = links
            .into_iter()
            .filter(|link| !self.seen.contains(link.as_str()))
            .collect();
        (new_count, new_links)
    }

    pub async fn run(&mut self, start_url: &Url) -> (usize, usize) {
        let mut queue: VecDeque<Url> = VecDeque::new();
        let start_url_owned = start_url.clone();
        queue.push_back(start_url_owned);

        let mut count = 0usize;
        let mut error_count = 0usize;
        let mut skipped_robots = 0usize;
        let mut skipped_scope = 0usize;
        let mut skipped_type = 0usize;

        while let Some(raw_url) = queue.pop_front() {
            let Some(url) = normalize_url(raw_url.as_str()) else {
                continue;
            };

            let url_key = url.as_str().to_string();

            if self.seen.contains(&url_key) {
                continue;
            }
            self.seen.insert(url_key.clone());

            if !is_in_scope(&url, self.scope_path.as_ref()) {
                log::debug!("[skip] out of scope: {url}");
                skipped_scope += 1;
                continue;
            }

            if !self.robots.is_allowed(url.path()) {
                log::info!("[skip] robots.txt disallows: {url}");
                skipped_robots += 1;
                continue;
            }

            log::info!("[{count}] fetching: {url}");

            match self.fetcher.fetch_with_retry(&url).await {
                Ok(result) => {
                    let final_url = result.final_url.clone();
                    let is_html = result.content_type.contains("text/html");

                    let (should_save, ext_label) =
                        self.should_save(&result.final_url, &result.content_type);

                    if !should_save {
                        log::info!("  skipped (type filter: {ext_label})");
                        skipped_type += 1;
                    }

                    if should_save {
                        match self.save(&result, is_html) {
                            Ok(()) => {
                                if !is_html {
                                    log::info!("  binary: {}", result.content_type);
                                }
                            }
                            Err(e) => {
                                log_error(
                                    &self.log_path,
                                    &final_url,
                                    "save_error",
                                    &e.to_string(),
                                    None,
                                );
                                error_count += 1;
                                self.doc_stats.errors += 1;
                            }
                        }
                    }

                    if is_html {
                        if self.single_page {
                            log::info!("  [single-page mode] not crawling for links");
                        } else if let Ok(html) = std::str::from_utf8(&result.bytes) {
                            let (new_count, new_links) = self.extract_new_links(html, &final_url);
                            for link in &new_links {
                                queue.push_back(link.clone());
                            }
                            log::info!("  found {new_count} links ({} new)", new_links.len());
                        }
                    }
                }
                Err(e) => {
                    log_error(&self.log_path, &url, "fetch_error", &e.to_string(), None);
                    error_count += 1;
                }
            }

            count += 1;
            tokio::time::sleep(Duration::from_millis(self.delay_ms)).await;
        }

        if self.doc_stats.converted > 0 || self.doc_stats.raw > 0 || self.doc_stats.errors > 0 {
            log::info!("\nDocument Statistics:");
            log::info!("  Converted to Markdown: {}", self.doc_stats.converted);
            log::info!("  Kept as-is:            {}", self.doc_stats.raw);
            log::info!("  Errors:                {}", self.doc_stats.errors);
        }

        if skipped_robots > 0 {
            log::info!("Skipped {skipped_robots} URLs due to robots.txt");
        }
        if skipped_scope > 0 {
            log::info!("Skipped {skipped_scope} URLs due to path scope");
        }
        if skipped_type > 0 {
            log::info!("Skipped {skipped_type} URLs due to type filter");
        }

        (count, error_count)
    }

    fn save(&mut self, result: &FetchResult, is_html: bool) -> Result<()> {
        let mut filename = url_to_filename(&result.final_url, &result.content_type);
        let content: Vec<u8>;

        if is_html {
            let html = std::str::from_utf8(&result.bytes)?;
            let md = html_to_markdown(html);
            if let Some(stripped) = filename.strip_suffix(".html") {
                filename = format!("{stripped}.md");
            }
            content = md.into_bytes();
        } else if self.convert_docs {
            match try_convert(&result.bytes, &result.final_url) {
                DocProcessResult::Markdown(md) => {
                    if let Some(pos) = filename.rfind('.') {
                        filename.truncate(pos);
                    }
                    filename.push_str(".md");
                    content = md.into_bytes();
                    log::info!("  [DOC] converted to Markdown");
                    self.doc_stats.converted += 1;
                }
                DocProcessResult::Raw => {
                    content = result.bytes.to_vec();
                    if is_document_content_type(&result.content_type) {
                        self.doc_stats.raw += 1;
                    }
                }
            }
        } else {
            content = result.bytes.to_vec();
        }

        let filepath = self.output_dir.join(&filename);
        fs::write(&filepath, &content)?;
        log::info!(
            "  saved -> {}",
            filepath.file_name().unwrap_or_default().to_string_lossy()
        );
        Ok(())
    }
}

fn is_document_content_type(ct: &str) -> bool {
    let ct = ct.split(';').next().unwrap_or("").trim().to_lowercase();
    DOC_TYPES.contains(&ct.as_str())
}

#[cfg(test)]
mod tests {
    use super::*;
    use reqwest::Client;
    use url::Url;

    fn make_scraper(
        include_types: Option<HashSet<String>>,
        exclude_types: Option<HashSet<String>>,
    ) -> Scraper {
        Scraper {
            fetcher: Fetcher::new(Client::new()),
            seen: HashSet::new(),
            output_dir: std::path::PathBuf::new(),
            log_path: std::path::PathBuf::new(),
            base_host: "example.com".to_string(),
            allow_subdomains: false,
            delay_ms: 1000,
            robots: RobotsRule {
                allowed: Vec::new(),
                disallowed: Vec::new(),
            },
            doc_stats: DocStats::default(),
            convert_docs: true,
            include_types,
            exclude_types,
            scope_path: None,
            single_page: false,
        }
    }

    #[test]
    fn test_should_save_include_only_matching() {
        let mut include = HashSet::new();
        include.insert("pdf".to_string());
        let scraper = make_scraper(Some(include), None);
        let url = Url::parse("https://example.com/doc.pdf").unwrap();
        let (should_save, ext) = scraper.should_save(&url, "application/pdf");
        assert!(should_save);
        assert_eq!(ext, "pdf");
    }

    #[test]
    fn test_should_save_include_non_matching() {
        let mut include = HashSet::new();
        include.insert("pdf".to_string());
        let scraper = make_scraper(Some(include), None);
        let url = Url::parse("https://example.com/doc.docx").unwrap();
        let (should_save, ext) = scraper.should_save(
            &url,
            "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
        );
        assert!(!should_save);
        assert_eq!(ext, "docx");
    }

    #[test]
    fn test_should_save_exclude_matching() {
        let mut exclude = HashSet::new();
        exclude.insert("pdf".to_string());
        let scraper = make_scraper(None, Some(exclude));
        let url = Url::parse("https://example.com/doc.pdf").unwrap();
        let (should_save, ext) = scraper.should_save(&url, "application/pdf");
        assert!(!should_save);
        assert_eq!(ext, "pdf");
    }

    #[test]
    fn test_should_save_exclude_non_matching() {
        let mut exclude = HashSet::new();
        exclude.insert("pdf".to_string());
        let scraper = make_scraper(None, Some(exclude));
        let url = Url::parse("https://example.com/doc.docx").unwrap();
        let (should_save, ext) = scraper.should_save(
            &url,
            "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
        );
        assert!(should_save);
        assert_eq!(ext, "docx");
    }

    #[test]
    fn test_should_save_no_filters_allows_all() {
        let scraper = make_scraper(None, None);
        let url = Url::parse("https://example.com/doc.pdf").unwrap();
        let (should_save, ext) = scraper.should_save(&url, "application/pdf");
        assert!(should_save);
        assert_eq!(ext, "pdf");
    }
}