use std::path::Path;

use crate::{
  cli::ExportArgs,
  error::{PakkerError, Result},
  export::Exporter,
  ipc::{IpcCoordinator, OperationType},
  model::{Config, LockFile, fork::LocalConfig},
  utils::hash::compute_sha256_bytes,
};

pub async fn execute(
  args: ExportArgs,
  lockfile_path: &Path,
  config_path: &Path,
) -> Result<()> {
  if let Some(ref profile) = args.profile {
    log::info!("Exporting with profile: {profile}");
  } else {
    log::info!("Exporting all profiles");
  }

  // Handle --no-server flag
  if args.no_server {
    log::info!("Server content will be excluded from export");
  }

  // Handle --show-io-errors flag
  let show_io_errors = args.show_io_errors;
  if show_io_errors {
    log::info!("IO errors will be shown during export");
  }

  let lockfile_dir = lockfile_path.parent().unwrap_or(Path::new("."));
  let config_dir = config_path.parent().unwrap_or(Path::new("."));

  // IPC coordination - prevent concurrent operations on the same modpack
  let ipc = IpcCoordinator::new(config_dir)?;
  let ipc_timeout = std::time::Duration::from_secs(60);

  // Check for conflicting export operations
  let conflicting = ipc.get_running_operations(OperationType::Export);
  if !conflicting.is_empty() {
    log::info!(
      "Waiting for conflicting operations to complete: {:?}",
      conflicting
        .iter()
        .map(|op| (op.id.clone(), op.pid))
        .collect::<Vec<_>>()
    );
    ipc
      .wait_for_conflicts(OperationType::Export, ipc_timeout)
      .await?;
  }

  // Register this export operation
  let _op_guard = ipc.register_operation(OperationType::Export)?;

  // Load config to check for fork configuration
  let config = Config::load(config_dir)?;
  let local_config = LocalConfig::load(config_dir).ok();

  // Check if this is a fork with parent
  let lockfile = if let Some(local_cfg) = &local_config {
    if local_cfg.parent.is_some() {
      log::info!("Fork detected - merging parent and local lockfiles");

      // Try parent's lockfile
      let parent_paths = [".pakku/parent", ".pakker/parent"];
      let mut parent_lockfile_path = None;
      let mut lockfile_name = "pakku-lock.json";

      for parent_dir in &parent_paths {
        // Try pakker-lock.json first
        let check_path = Path::new(parent_dir).join("pakker-lock.json");
        if check_path.exists() {
          parent_lockfile_path = Some(parent_dir);
          lockfile_name = "pakker-lock.json";
          break;
        }
        // Fall back to pakku-lock.json
        let check_path = Path::new(parent_dir).join("pakku-lock.json");
        if check_path.exists() {
          parent_lockfile_path = Some(parent_dir);
          lockfile_name = "pakku-lock.json";
          break;
        }
      }

      if let Some(parent_dir) = parent_lockfile_path {
        // Load parent lockfile
        let parent_lockfile = LockFile::load(Path::new(parent_dir))?;

        // Verify parent lockfile hash for integrity
        if let Some(stored_hash) = &local_cfg.parent_lock_hash {
          let parent_lock_path = Path::new(parent_dir).join(lockfile_name);
          let parent_lock_content = std::fs::read(&parent_lock_path)?;
          let computed_hash = compute_sha256_bytes(&parent_lock_content);

          if &computed_hash != stored_hash {
            log::warn!(
              "Parent lockfile hash mismatch - parent may have changed since \
               last sync"
            );
            log::warn!("Expected: {stored_hash}, Got: {computed_hash}");
          }
        }

        // Load local lockfile if it exists
        if lockfile_path.exists() {
          log::info!("Merging parent lockfile with local overrides");
          let local_lockfile =
            LockFile::load_with_validation(lockfile_dir, false)?;

          // Merge: start with parent, override with local
          merge_lockfiles(parent_lockfile, local_lockfile, local_cfg)?
        } else {
          log::info!("No local lockfile - using parent lockfile");
          parent_lockfile
        }
      } else {
        return Err(PakkerError::IoError(std::io::Error::new(
          std::io::ErrorKind::NotFound,
          "Fork configured but parent lockfile not found",
        )));
      }
    } else {
      // No fork, use local lockfile
      if lockfile_path.exists() {
        LockFile::load(lockfile_dir)?
      } else {
        return Err(PakkerError::IoError(std::io::Error::new(
          std::io::ErrorKind::NotFound,
          "No lockfile found",
        )));
      }
    }
  } else {
    // No local config, try local lockfile or fall back to parent
    if lockfile_path.exists() {
      LockFile::load(lockfile_dir)?
    } else {
      // Try parent's lockfile as fallback
      let parent_paths = [".pakku/parent", ".pakker/parent"];
      let mut parent_lockfile = None;
      let mut lockfile_name = "pakku-lock.json";

      for parent_dir in &parent_paths {
        // Try pakker-lock.json first
        let lockfile_path_check =
          Path::new(parent_dir).join("pakker-lock.json");
        if lockfile_path_check.exists() {
          parent_lockfile = Some(parent_dir);
          lockfile_name = "pakker-lock.json";
          break;
        }
        // Fall back to pakku-lock.json
        let lockfile_path_check = Path::new(parent_dir).join("pakku-lock.json");
        if lockfile_path_check.exists() {
          parent_lockfile = Some(parent_dir);
          lockfile_name = "pakku-lock.json";
          break;
        }
      }

      match parent_lockfile {
        Some(parent_dir) => {
          log::info!(
            "Using parent's lockfile ({lockfile_name}) from {parent_dir}"
          );
          LockFile::load(Path::new(parent_dir))?
        },
        None => {
          return Err(PakkerError::IoError(std::io::Error::new(
            std::io::ErrorKind::NotFound,
            "No lockfile found (neither local nor parent's)",
          )));
        },
      }
    }
  };

  // Determine output path
  let output_path = if args.pakker_layout {
    "build"
  } else {
    args.output.as_deref().unwrap_or("exports")
  };

  // Create exporter
  let mut exporter = Exporter::new(".");

  // Export based on profile argument
  if let Some(profile_name) = args.profile {
    // Single profile export (backwards compatible)
    let output_file = exporter
      .export(&profile_name, &lockfile, &config, Path::new(output_path))
      .await?;

    println!("Export complete: {output_file:?}");
  } else {
    // Multi-profile export (Pakker-compatible default behavior)
    let output_files = exporter
      .export_all_profiles(&lockfile, &config, Path::new(output_path))
      .await?;

    println!("\nExported {} files:", output_files.len());
    for output_file in output_files {
      println!("  - {output_file:?}");
    }
  }

  Ok(())
}

/// Merges parent lockfile with local lockfile
/// Parent projects are used as base, local projects override parent projects
/// with same slug
fn merge_lockfiles(
  parent: LockFile,
  local: LockFile,
  local_config: &LocalConfig,
) -> Result<LockFile> {
  let mut merged = LockFile {
    target:           parent.target, // Use parent target
    mc_versions:      parent.mc_versions, // Use parent MC versions
    loaders:          parent.loaders, // Use parent loaders
    projects:         Vec::new(),
    lockfile_version: parent.lockfile_version,
  };

  // Collect local project slugs for override detection
  let mut local_slugs = std::collections::HashSet::new();
  for project in &local.projects {
    // Add all slugs from all platforms
    for slug in project.slug.values() {
      local_slugs.insert(slug.clone());
    }
  }

  // Add parent projects that are NOT overridden by local
  let parent_projects_count = parent.projects.len();

  for parent_project in &parent.projects {
    let is_overridden = parent_project
      .slug
      .values()
      .any(|slug| local_slugs.contains(slug));

    if !is_overridden {
      // Check if project has local config overrides
      let mut project = parent_project.clone();

      // Apply local config overrides if they exist
      for (key, local_proj_cfg) in &local_config.projects {
        // Match by slug, name, or pakku_id
        let matches = project.slug.values().any(|s| s == key)
          || project.name.values().any(|n| n == key)
          || project.pakku_id.as_ref() == Some(key);

        if matches {
          if let Some(t) = local_proj_cfg.r#type {
            project.r#type = t;
          }
          if let Some(s) = local_proj_cfg.side {
            project.side = s;
          }
          if let Some(us) = local_proj_cfg.update_strategy {
            project.update_strategy = us;
          }
          if let Some(r) = local_proj_cfg.redistributable {
            project.redistributable = r;
          }
          if let Some(ref sp) = local_proj_cfg.subpath {
            project.subpath = Some(sp.clone());
          }
          if let Some(ref aliases) = local_proj_cfg.aliases {
            project.aliases = aliases.iter().cloned().collect();
          }
          if let Some(e) = local_proj_cfg.export {
            project.export = e;
          }
          break;
        }
      }

      merged.projects.push(project);
    }
  }

  // Add all local projects
  merged.projects.extend(local.projects.clone());

  println!(
    "Merged fork: {} parent projects + {} local projects = {} total projects",
    parent_projects_count - local_config.projects.len(),
    local.projects.len(),
    merged.projects.len()
  );

  Ok(merged)
}