use flate2::Compression;
use flate2::read::GzDecoder;
use flate2::write::GzEncoder;
use rusqlite::Connection;
use rusqlite::OptionalExtension;
use sha2::{Digest, Sha256};
use std::io::{Read, Write};

use super::error::Result;
use super::time::now_ms;

pub struct StorePayloadOptions<'a> {
    pub project_id: Option<i64>,
    pub resource_type: &'a str,
    pub gitlab_id: &'a str,
    pub json_bytes: &'a [u8],
    pub compress: bool,
}

pub fn store_payload(conn: &Connection, options: StorePayloadOptions) -> Result<i64> {
    let json_bytes = options.json_bytes;

    let mut hasher = Sha256::new();
    hasher.update(json_bytes);
    let payload_hash = format!("{:x}", hasher.finalize());

    let existing: Option<i64> = conn
        .query_row(
            "SELECT id FROM raw_payloads
             WHERE project_id IS ? AND resource_type = ? AND gitlab_id = ? AND payload_hash = ?",
            (
                options.project_id,
                options.resource_type,
                options.gitlab_id,
                &payload_hash,
            ),
            |row| row.get(0),
        )
        .optional()?;

    if let Some(id) = existing {
        return Ok(id);
    }

    let (encoding, payload_bytes): (&str, std::borrow::Cow<'_, [u8]>) = if options.compress {
        let mut encoder = GzEncoder::new(Vec::new(), Compression::default());
        encoder.write_all(json_bytes)?;
        ("gzip", std::borrow::Cow::Owned(encoder.finish()?))
    } else {
        ("identity", std::borrow::Cow::Borrowed(json_bytes))
    };

    conn.execute(
        "INSERT INTO raw_payloads
         (source, project_id, resource_type, gitlab_id, fetched_at, content_encoding, payload_hash, payload)
         VALUES ('gitlab', ?, ?, ?, ?, ?, ?, ?)",
        (
            options.project_id,
            options.resource_type,
            options.gitlab_id,
            now_ms(),
            encoding,
            &payload_hash,
            payload_bytes.as_ref(),
        ),
    )?;

    Ok(conn.last_insert_rowid())
}

pub fn read_payload(conn: &Connection, id: i64) -> Result<Option<serde_json::Value>> {
    let row: Option<(String, Vec<u8>)> = conn
        .query_row(
            "SELECT content_encoding, payload FROM raw_payloads WHERE id = ?",
            [id],
            |row| Ok((row.get(0)?, row.get(1)?)),
        )
        .optional()?;

    let Some((encoding, payload_bytes)) = row else {
        return Ok(None);
    };

    let json_bytes = if encoding == "gzip" {
        let mut decoder = GzDecoder::new(&payload_bytes[..]);
        let mut decompressed = Vec::new();
        decoder.read_to_end(&mut decompressed)?;
        decompressed
    } else {
        payload_bytes
    };

    let value: serde_json::Value = serde_json::from_slice(&json_bytes)?;
    Ok(Some(value))
}

#[cfg(test)]
#[path = "payloads_tests.rs"]
mod tests;