use futures::future::join_all;
use just_progress::progress;
use log::{debug, error, trace};
use std::{
    collections::HashMap,
    path::{Path, PathBuf},
};
use tokio::{fs::File, io::AsyncReadExt};

use crate::{
    chunker::{
        context::ButckContext,
        rw::{
            error::ButckRWErrorKind,
            storage::{self, ChunkInfo, bidx::write_bidx_file, hash::ChunkWriteHash},
        },
    },
    storage::{display_boundaries, get_index_file_name},
};

pub async fn write_file_simple(
    path: &PathBuf,
    ctx: &ButckContext,
    params: &HashMap<&str, &str>,
) -> Result<(), ButckRWErrorKind> {
    read_file(path, ctx, params).await?;
    Ok(())
}

async fn read_file(
    path: &PathBuf,
    ctx: &ButckContext,
    params: &HashMap<&str, &str>,
) -> Result<(), ButckRWErrorKind> {
    let mut file = File::open(path).await?;

    // Use butck_policies::chunk_with to locate chunk boundaries in the file
    if ctx.memmap_read {
        let mmap = unsafe { memmap2::Mmap::map(&file)? };
        let raw_data = &mmap[..];
        let (chunk_boundaries, total_bytes) =
            (get_boundaries(raw_data, ctx, params).await?, raw_data.len());

        // If output boundaries, do not execute actual write logic
        if ctx.display_boundaries {
            display_boundaries(&chunk_boundaries, total_bytes).await;
            return Ok(());
        } else {
            write_file_to_storage(path, ctx, chunk_boundaries, raw_data).await?;
        }
    } else {
        let mut contents = Vec::new();
        file.read_to_end(&mut contents).await?;
        let raw_data = &contents[..];
        let (chunk_boundaries, total_bytes) =
            (get_boundaries(raw_data, ctx, params).await?, raw_data.len());

        // If output boundaries, do not execute actual write logic
        if ctx.display_boundaries {
            display_boundaries(&chunk_boundaries, total_bytes).await;
            return Ok(());
        } else {
            write_file_to_storage(path, ctx, chunk_boundaries, raw_data).await?;
        }
    };
    progress::clear_all();
    Ok(())
}

async fn write_file_to_storage(
    path: &Path,
    ctx: &ButckContext,
    chunk_boundaries: Vec<u32>,
    raw_data: &[u8],
) -> Result<(), ButckRWErrorKind> {
    let output_index_file = get_index_file_name(path, ctx);

    let chunk_count = chunk_boundaries.len() + 1;
    let progress_name = format!("Write `{}`", path.display());

    progress::update_progress(progress_name.as_str(), 0.0);
    let step = 1.0 / chunk_count as f64;

    trace!("chunks_count={}", chunk_count);
    trace!("chunk_hash={:?}", ctx.chunk_hash);
    trace!("file_size={}", raw_data.len());
    trace!("output_index_file={}", output_index_file.display());
    trace!("policy_name={:?}", ctx.policy_name);
    trace!(
        "storage_dir={}",
        ctx.storage_path.as_ref().unwrap().display()
    );

    debug!(
        "{} chunks will be written to {}",
        chunk_count,
        ctx.storage_path.as_ref().unwrap().display()
    );

    let storage_dir = ctx.storage_path.as_ref().unwrap().clone();
    tokio::fs::create_dir_all(&storage_dir).await?;
    trace!("Storage directory created or already exists");

    let mut tasks = Vec::new();
    let mut start = 0;
    let mut chunk_index = 0;

    trace!("Processing chunk boundaries:");

    for &boundary in &chunk_boundaries {
        let end = boundary as usize;
        if start < end && end <= raw_data.len() {
            let chunk_data = &raw_data[start..end];
            trace!(
                "Chunk {}: bytes {}..{} (size: {} bytes)",
                chunk_index,
                start,
                end - 1,
                end - start
            );
            let params = WriteChunkParams {
                progress_name: progress_name.clone(),
                step,
                chunk_data: chunk_data.to_vec(),
                output_dir: ctx.storage_path.as_ref().unwrap().clone(),
                chunk_hash: ctx.chunk_hash,
                chunk_index,
            };
            tasks.push(write_chunk(params));
            chunk_index += 1;
        } else {
            trace!(
                "Skipping invalid chunk boundary: start={}, end={}, data_len={}",
                start,
                end,
                raw_data.len()
            );
        }
        start = end;
    }

    if start < raw_data.len() {
        let chunk_data = &raw_data[start..];
        trace!(
            "Chunk {}: bytes {}..{} (size: {} bytes) - final chunk",
            chunk_index,
            start,
            raw_data.len() - 1,
            raw_data.len() - start
        );
        let params = WriteChunkParams {
            progress_name: progress_name.clone(),
            step,
            chunk_data: chunk_data.to_vec(),
            output_dir: ctx.storage_path.as_ref().unwrap().clone(),
            chunk_hash: ctx.chunk_hash,
            chunk_index,
        };
        tasks.push(write_chunk(params));
    }

    trace!("Total chunks prepared for writing: {}", tasks.len());

    trace!("Starting parallel write of {} chunks", tasks.len());
    let results = join_all(tasks).await;
    trace!("All write tasks completed");

    let mut success_count = 0;
    let mut chunk_infos = Vec::new();

    for result in results {
        match result {
            Ok(chunk_info) => {
                success_count += 1;
                chunk_infos.push(chunk_info);
            }
            Err(e) => {
                trace!("Chunk write failed: {:?}", e);
                return Err(e);
            }
        }
    }

    debug!("All {} chunks written successfully", success_count);

    // Write index file
    trace!("Writing index file to: {}", output_index_file.display());
    if let Err(e) = write_index_file(&output_index_file, &chunk_infos, path).await {
        error!("Failed to write index file: {}", e);
        return Err(ButckRWErrorKind::IOError(e));
    }
    debug!("Index file written to: {}", output_index_file.display());

    trace!("write_file_to_storage completed successfully");

    progress::complete(progress_name.as_str());

    Ok(())
}

struct WriteChunkParams {
    progress_name: String,
    step: f64,
    chunk_data: Vec<u8>,
    output_dir: PathBuf,
    chunk_hash: ChunkWriteHash,
    chunk_index: usize,
}

async fn write_chunk(params: WriteChunkParams) -> Result<ChunkInfo, ButckRWErrorKind> {
    trace!(
        "write_chunk[{}]: Starting, data size: {} bytes",
        params.chunk_index,
        params.chunk_data.len()
    );

    trace!(
        "write_chunk[{}]: Computing hash with algorithm: {:?}",
        params.chunk_index, params.chunk_hash
    );
    let hash_bytes = params.chunk_hash.hash(&params.chunk_data);
    trace!(
        "write_chunk[{}]: Hash computed: {:?}",
        params.chunk_index, hash_bytes
    );

    let hash_hex = hex::encode(hash_bytes);
    trace!(
        "write_chunk[{}]: Hash hex: {}",
        params.chunk_index, hash_hex
    );

    let file_path = storage::get_chunk_path(&params.output_dir, &hash_hex);

    if let Some(parent_dir) = file_path.parent() {
        trace!(
            "write_chunk[{}]: Creating directory structure: {}",
            params.chunk_index,
            parent_dir.display()
        );
        tokio::fs::create_dir_all(parent_dir).await?;
        trace!("write_chunk[{}]: Directory created", params.chunk_index);
    }

    trace!(
        "write_chunk[{}]: File path: {}",
        params.chunk_index,
        file_path.display()
    );

    trace!(
        "write_chunk[{}]: Writing {} bytes to file",
        params.chunk_index,
        params.chunk_data.len()
    );

    progress::increase(&params.progress_name, params.step as f32);

    if !file_path.exists() {
        tokio::fs::write(&file_path, &params.chunk_data).await?;
    } else {
        trace!(
            "write_chunk[{}]: File already exists, skipping",
            params.chunk_index
        );
    }
    trace!(
        "write_chunk[{}]: File written successfully",
        params.chunk_index
    );
    Ok(ChunkInfo {
        index: params.chunk_index,
        hash: hash_hex,
    })
}

async fn get_boundaries(
    raw_data: &[u8],
    ctx: &ButckContext,
    params: &HashMap<&str, &str>,
) -> Result<Vec<u32>, ButckRWErrorKind> {
    let policy_name = ctx.policy_name.as_ref().unwrap().as_str();
    match butck_policies::chunk_with(policy_name, raw_data, params).await {
        Ok(s) => Ok(s),
        Err(e) => Err(ButckRWErrorKind::ChunkFailed(e)),
    }
}

async fn write_index_file(
    index_path: &Path,
    chunk_infos: &[ChunkInfo],
    original_file_path: &Path,
) -> Result<(), std::io::Error> {
    write_bidx_file(index_path, chunk_infos, original_file_path)
}