package daemon

import (
	"fmt"
	"os"
	"path/filepath"
	"time"

	"git.dws.rip/DWS/onyx/internal/git"
	"git.dws.rip/DWS/onyx/internal/models"
	gogit "github.com/go-git/go-git/v5"
	"github.com/go-git/go-git/v5/plumbing/filemode"
)

const (
	// OnyxWorkspaceRef is the ref where ephemeral commits are stored
	OnyxWorkspaceRef = "refs/onyx/workspaces/current"
)

// CreateSnapshot creates an ephemeral commit representing the current workspace state
func (d *Daemon) CreateSnapshot() error {
	// 1. Read current workspace pointer
	workspaceState, err := d.readWorkspaceState()
	if err != nil {
		// If workspace doesn't exist, create a new one
		workspaceState = models.NewWorkspaceState("", "main")
	}

	// 2. Create tree from working directory
	gitBackend := git.NewGitBackend(d.repo.GetGitRepo())
	repoRoot := filepath.Dir(d.repo.GetOnyxPath())

	treeHash, err := d.createWorkspaceTree(repoRoot)
	if err != nil {
		return fmt.Errorf("failed to create workspace tree: %w", err)
	}

	// 3. Get the parent commit (if it exists)
	var parentHash string
	if workspaceState.CurrentCommitSHA != "" {
		parentHash = workspaceState.CurrentCommitSHA
	} else {
		// Try to get the current HEAD commit as parent
		head, err := d.repo.GetGitRepo().Head()
		if err == nil {
			parentHash = head.Hash().String()
		}
	}

	// 4. Create ephemeral commit
	message := fmt.Sprintf("[onyx-snapshot] Auto-save at %s", time.Now().Format("2006-01-02 15:04:05"))
	commitHash, err := gitBackend.CreateCommit(treeHash, parentHash, message, "Onyx Daemon")
	if err != nil {
		return fmt.Errorf("failed to create commit: %w", err)
	}

	// 5. Update refs/onyx/workspaces/current
	if err := gitBackend.UpdateRef(OnyxWorkspaceRef, commitHash); err != nil {
		return fmt.Errorf("failed to update workspace ref: %w", err)
	}

	// 6. Update .onx/workspace pointer
	workspaceState.UpdateSnapshot(commitHash, treeHash, "", false)
	if err := d.saveWorkspaceState(workspaceState); err != nil {
		return fmt.Errorf("failed to save workspace state: %w", err)
	}

	return nil
}

// createWorkspaceTree creates a Git tree object from the current working directory
func (d *Daemon) createWorkspaceTree(rootPath string) (string, error) {
	gitBackend := git.NewGitBackend(d.repo.GetGitRepo())

	// Use the worktree to build the tree
	worktree, err := d.repo.GetGitRepo().Worktree()
	if err != nil {
		return "", fmt.Errorf("failed to get worktree: %w", err)
	}

	// Create tree entries by walking the working directory
	entries := []git.TreeEntry{}

	err = filepath.Walk(rootPath, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}

		// Skip the root directory itself
		if path == rootPath {
			return nil
		}

		// Get relative path
		relPath, err := filepath.Rel(rootPath, path)
		if err != nil {
			return err
		}

		// Skip .git and .onx directories
		if shouldIgnorePath(path) {
			if info.IsDir() {
				return filepath.SkipDir
			}
			return nil
		}

		// For now, we'll use a simplified approach: hash the file content
		if !info.IsDir() {
			content, err := os.ReadFile(path)
			if err != nil {
				return fmt.Errorf("failed to read file %s: %w", path, err)
			}

			// Create blob for file content
			blobHash, err := gitBackend.CreateBlob(content)
			if err != nil {
				return fmt.Errorf("failed to create blob for %s: %w", path, err)
			}

			// Determine file mode
			mode := filemode.Regular
			if info.Mode()&0111 != 0 {
				mode = filemode.Executable
			}

			entries = append(entries, git.TreeEntry{
				Name: relPath,
				Mode: mode,
				Hash: git.HashFromString(blobHash),
			})
		}

		return nil
	})

	if err != nil {
		return "", fmt.Errorf("failed to walk directory: %w", err)
	}

	// For a proper implementation, we'd need to build a hierarchical tree
	// For now, we'll use the worktree's tree builder
	return d.buildTreeFromWorktree(worktree)
}

// buildTreeFromWorktree builds a tree object from the current worktree state
func (d *Daemon) buildTreeFromWorktree(worktree *gogit.Worktree) (string, error) {
	// Get the current index/staging area state
	// This is a simplified version - in production we'd want to properly handle
	// all files in the working directory

	// For now, get the HEAD tree as a base
	head, err := d.repo.GetGitRepo().Head()
	if err != nil {
		// No HEAD yet (empty repo), return empty tree
		return d.createEmptyTree()
	}

	commit, err := d.repo.GetGitRepo().CommitObject(head.Hash())
	if err != nil {
		return "", fmt.Errorf("failed to get HEAD commit: %w", err)
	}

	tree, err := commit.Tree()
	if err != nil {
		return "", fmt.Errorf("failed to get commit tree: %w", err)
	}

	// For now, just return the HEAD tree hash
	// In a full implementation, we'd modify this tree based on working directory changes
	return tree.Hash.String(), nil
}

// createEmptyTree creates an empty Git tree object
func (d *Daemon) createEmptyTree() (string, error) {
	gitBackend := git.NewGitBackend(d.repo.GetGitRepo())
	return gitBackend.CreateTree([]git.TreeEntry{})
}

// readWorkspaceState reads the workspace state from .onx/workspace
func (d *Daemon) readWorkspaceState() (*models.WorkspaceState, error) {
	workspacePath := filepath.Join(d.repo.GetOnyxPath(), "workspace")

	data, err := os.ReadFile(workspacePath)
	if err != nil {
		return nil, fmt.Errorf("failed to read workspace file: %w", err)
	}

	state, err := models.DeserializeWorkspaceState(data)
	if err != nil {
		return nil, fmt.Errorf("failed to deserialize workspace state: %w", err)
	}

	return state, nil
}

// saveWorkspaceState saves the workspace state to .onx/workspace
func (d *Daemon) saveWorkspaceState(state *models.WorkspaceState) error {
	workspacePath := filepath.Join(d.repo.GetOnyxPath(), "workspace")

	data, err := state.Serialize()
	if err != nil {
		return fmt.Errorf("failed to serialize workspace state: %w", err)
	}

	if err := os.WriteFile(workspacePath, data, 0644); err != nil {
		return fmt.Errorf("failed to write workspace file: %w", err)
	}

	return nil
}