package prompt

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"sync"

	"github.com/opencode-ai/opencode/internal/config"
	"github.com/opencode-ai/opencode/internal/llm/models"
)

func GetAgentPrompt(agentName config.AgentName, provider models.ModelProvider) string {
	basePrompt := ""
	switch agentName {
	case config.AgentCoder:
		basePrompt = CoderPrompt(provider)
	case config.AgentTitle:
		basePrompt = TitlePrompt(provider)
	case config.AgentTask:
		basePrompt = TaskPrompt(provider)
	default:
		basePrompt = "You are a helpful assistant"
	}

	if agentName == config.AgentCoder || agentName == config.AgentTask {
		// Add context from project-specific instruction files if they exist
		contextContent := getContextFromPaths()
		if contextContent != "" {
			return fmt.Sprintf("%s\n\n# Project-Specific Context\n Make sure to follow the instructions in the context below\n%s", basePrompt, contextContent)
		}
	}
	return basePrompt
}

var (
	onceContext    sync.Once
	contextContent string
)

func getContextFromPaths() string {
	onceContext.Do(func() {
		var (
			cfg          = config.Get()
			workDir      = cfg.WorkingDir
			contextPaths = cfg.ContextPaths
		)

		contextContent = processContextPaths(workDir, contextPaths)
	})

	return contextContent
}

func processContextPaths(workDir string, paths []string) string {
	var (
		wg       sync.WaitGroup
		resultCh = make(chan string)
	)

	for _, path := range paths {
		wg.Add(1)
		go func(p string) {
			defer wg.Done()

			if strings.HasSuffix(p, "/") {
				filepath.WalkDir(filepath.Join(workDir, p), func(path string, d os.DirEntry, err error) error {
					if err != nil {
						return err
					}
					if !d.IsDir() {
						if result := processFile(path); result != "" {
							resultCh <- result
						}
					}
					return nil
				})
			} else {
				result := processFile(filepath.Join(workDir, p))
				if result != "" {
					resultCh <- result
				}
			}
		}(path)
	}

	go func() {
		wg.Wait()
		close(resultCh)
	}()

	results := make([]string, 0)
	for result := range resultCh {
		results = append(results, result)
	}

	return strings.Join(results, "\n")
}

func processFile(filePath string) string {
	content, err := os.ReadFile(filePath)
	if err != nil {
		return ""
	}
	return "# From:" + filePath + "\n" + string(content)
}