use anyhow::Result;
use tokio::time::Instant;
use tracing::{debug_span, trace};

use crate::{
    blob::{Blob, BlobMetadata},
    content_type::ContentInspector,
    location::LocationMapping,
    matcher::{Match, Matcher, OwnedBlobMatch, ScanResult},
    origin::{Origin, OriginSet},
    scanner::repos::DatastoreMessage,
    Path,
};

const LOCATION_LIMIT_BYTES: usize = 256 * 1024 * 1024;

/// A matcher along with parameters that remain constant during a single
/// `scan` run
pub struct BlobProcessor<'a> {
    pub matcher: Matcher<'a>,
}

impl<'a> BlobProcessor<'a> {
    pub fn run(
        &mut self,
        origin: OriginSet,
        blob: Blob,
        no_dedup: bool,
        redact: bool,
        no_base64: bool,
    ) -> Result<Option<DatastoreMessage>> {
        let _span = debug_span!("matcher", temp_id = blob.temp_id()).entered();
        let t1 = Instant::now();
        let language_hint = origin
            .iter()
            .find_map(|p| p.blob_path())
            .and_then(|path| ContentInspector::default().guess_language(path, blob.bytes()));
        let res =
            self.matcher.scan_blob(&blob, &origin, language_hint, redact, no_dedup, no_base64)?;
        let scan_us = t1.elapsed().as_micros();
        match res {
            // blob already seen, but with no matches; nothing to do!
            ScanResult::SeenSansMatches => {
                trace!("({scan_us}us) blob already scanned with no matches");
                Ok(None)
            }

            // blob already seen; all we need to do is record its origin
            ScanResult::SeenWithMatches => {
                trace!("({scan_us}us) blob already scanned with matches");
                let metadata = BlobMetadata {
                    id: blob.id(),
                    num_bytes: blob.len(),
                    mime_essence: None,
                    language: None,
                };
                Ok(Some((origin, metadata, Vec::new())))
            }

            // blob has not been seen; need to record blob metadata, origin, and matches
            ScanResult::New(matches) => {
                trace!("({scan_us}us) blob newly scanned; {} matches", matches.len());
                // If there are no matches, we can bail out here and avoid recording anything.
                // UNLESS the `--blob-metadata=all` mode was specified; then we need to record
                // the origin for _all_ seen blobs.
                if matches.is_empty() {
                    return Ok(None);
                }
                let md = MetadataResult::from_blob_and_origin(&blob, &origin);
                let metadata = BlobMetadata {
                    id: blob.id(),
                    num_bytes: blob.len(),
                    mime_essence: md.mime_essence,
                    language: md.language,
                };

                let mut origin_type = "unknown";
                for origin_entry in origin.iter() {
                    let type_str = match origin_entry {
                        Origin::GitRepo(_) => "git",
                        Origin::File(_) => "file",
                        Origin::Extended(_) => "ext",
                    };
                    // println!("Origin type: {}", type_str);
                    if origin_type == "unknown" {
                        origin_type = type_str;
                        break; // Exit loop after first match
                    }
                }

                let bytes = blob.bytes();
                let loc_mapping = if bytes.len() <= LOCATION_LIMIT_BYTES {
                    Some(LocationMapping::new(bytes))
                } else {
                    None
                };
                let converted_matches: Vec<(Option<f64>, Match)> = matches
                    .into_iter()
                    .map(|m| {
                        let converted_match = Match::convert_owned_blobmatch_to_match(
                            loc_mapping.as_ref(),
                            &OwnedBlobMatch::from_blob_match(m),
                            origin_type,
                        );
                        (None, converted_match)
                    })
                    .collect();
                Ok(Some((origin, metadata, converted_matches)))
            }
        }
    }
}

#[derive(Default)]
struct MetadataResult {
    mime_essence: Option<String>,
    language: Option<String>,
}
impl MetadataResult {
    fn from_blob_and_origin(blob: &Blob, origin: &OriginSet) -> MetadataResult {
        let blob_path: Option<&'_ Path> = origin.iter().find_map(|p| p.blob_path());
        let bytes = blob.bytes();
        let mime_essence = Some(tree_magic_mini::from_u8(bytes).to_string());
        let inspector = ContentInspector::default();
        let language = blob_path.and_then(|p| inspector.guess_language(p, bytes));
        MetadataResult { mime_essence, language }
    }
}