package router

import (
	"os"
	"strings"
	"time"
)

// compileWithMiddleware combines middleware and handler source, then compiles
func (r *LuaRouter) compileWithMiddleware(n *node, fsPath, scriptPath string) error {
	if scriptPath == "" {
		return nil
	}

	// Check if we need to recompile by comparing modification times
	sourceKey := r.getSourceCacheKey(fsPath, scriptPath)
	needsRecompile := false

	// Check handler modification time
	handlerInfo, err := os.Stat(scriptPath)
	if err != nil {
		n.err = err
		return err
	}

	lastCompiled, exists := r.sourceMtimes[sourceKey]
	if !exists || handlerInfo.ModTime().After(lastCompiled) {
		needsRecompile = true
	}

	// Check middleware modification times
	if !needsRecompile {
		middlewareChain := r.getMiddlewareChain(fsPath)
		for _, mwPath := range middlewareChain {
			mwInfo, err := os.Stat(mwPath)
			if err != nil {
				n.err = err
				return err
			}
			if mwInfo.ModTime().After(lastCompiled) {
				needsRecompile = true
				break
			}
		}
	}

	// Use cached bytecode if available and fresh
	if !needsRecompile {
		if bytecode, exists := r.sourceCache[sourceKey]; exists {
			bytecodeKey := getBytecodeKey(scriptPath)
			r.bytecodeCache.Set(bytecodeKey, bytecode)
			return nil
		}
	}

	// Build combined source
	combinedSource, err := r.buildCombinedSource(fsPath, scriptPath)
	if err != nil {
		n.err = err
		return err
	}

	// Compile combined source using shared state
	r.compileStateMu.Lock()
	bytecode, err := r.compileState.CompileBytecode(combinedSource, scriptPath)
	r.compileStateMu.Unlock()

	if err != nil {
		n.err = err
		return err
	}

	// Cache everything
	bytecodeKey := getBytecodeKey(scriptPath)
	r.bytecodeCache.Set(bytecodeKey, bytecode)
	r.sourceCache[sourceKey] = bytecode
	r.sourceMtimes[sourceKey] = time.Now()

	n.err = nil
	return nil
}

// buildCombinedSource builds the combined middleware + handler source
func (r *LuaRouter) buildCombinedSource(fsPath, scriptPath string) (string, error) {
	var combinedSource strings.Builder

	// Get middleware chain using filesystem path
	middlewareChain := r.getMiddlewareChain(fsPath)

	// Add middleware in order
	for _, mwPath := range middlewareChain {
		content, err := r.getFileContent(mwPath)
		if err != nil {
			return "", err
		}
		combinedSource.WriteString("-- Middleware: ")
		combinedSource.WriteString(mwPath)
		combinedSource.WriteString("\n")
		combinedSource.Write(content)
		combinedSource.WriteString("\n")
	}

	// Add main handler
	content, err := r.getFileContent(scriptPath)
	if err != nil {
		return "", err
	}
	combinedSource.WriteString("-- Handler: ")
	combinedSource.WriteString(scriptPath)
	combinedSource.WriteString("\n")
	combinedSource.Write(content)

	return combinedSource.String(), nil
}

// getFileContent reads file content with caching
func (r *LuaRouter) getFileContent(path string) ([]byte, error) {
	// Check cache first
	if content, exists := r.middlewareCache[path]; exists {
		// Verify file hasn't changed
		info, err := os.Stat(path)
		if err == nil {
			if cachedTime, exists := r.sourceMtimes[path]; exists && !info.ModTime().After(cachedTime) {
				return content, nil
			}
		}
	}

	// Read from disk
	content, err := os.ReadFile(path)
	if err != nil {
		return nil, err
	}

	// Cache it
	r.middlewareCache[path] = content
	r.sourceMtimes[path] = time.Now()

	return content, nil
}

// getSourceCacheKey generates a unique key for combined source
func (r *LuaRouter) getSourceCacheKey(fsPath, scriptPath string) string {
	middlewareChain := r.getMiddlewareChain(fsPath)
	var keyParts []string
	keyParts = append(keyParts, middlewareChain...)
	keyParts = append(keyParts, scriptPath)
	return strings.Join(keyParts, "|")
}

// getMiddlewareChain returns middleware files that apply to the given filesystem path
func (r *LuaRouter) getMiddlewareChain(fsPath string) []string {
	var chain []string

	// Collect middleware from root to specific path using filesystem path (includes groups)
	pathParts := strings.Split(strings.Trim(fsPath, "/"), "/")
	if pathParts[0] == "" {
		pathParts = []string{}
	}

	// Add root middleware
	if mw, exists := r.middlewareFiles["/"]; exists {
		chain = append(chain, mw...)
	}

	// Add middleware from each path level (including groups)
	currentPath := ""
	for _, part := range pathParts {
		currentPath += "/" + part
		if mw, exists := r.middlewareFiles[currentPath]; exists {
			chain = append(chain, mw...)
		}
	}

	return chain
}