package template

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

	"chat-agent-system/internal/workflowdef"
	"chat-agent-system/templates"
)

func findProjectRoot() string {
	wd, _ := os.Getwd()
	candidates := []string{wd}
	dir := wd
	for i := 0; i < 10; i++ {
		candidates = append(candidates, dir)
		parent := filepath.Dir(dir)
		if parent == dir {
			break
		}
		dir = parent
	}
	if env := strings.TrimSpace(os.Getenv("APP_ROOT")); env != "" {
		candidates = append(candidates, env)
	}
	// Image WORKDIR is /app; Dockerfile copies templates/configs here.
	candidates = append(candidates, "/app")
	for _, root := range candidates {
		if root == "" {
			continue
		}
		if _, err := os.Stat(filepath.Join(root, "templates", "docs")); err == nil {
			return root
		}
	}
	return wd
}

func GetDocTemplate(name string) (string, error) {
	name = strings.TrimSuffix(name, ".md")
	if name == "" || strings.Contains(name, "..") || strings.ContainsAny(name, `/\`) {
		return "", fmt.Errorf("read doc template: invalid name %q", name)
	}
	for _, candidate := range templateNames(name) {
		if b, err := templates.DocTemplates.ReadFile("docs/" + candidate + ".md"); err == nil && len(strings.TrimSpace(string(b))) > 0 {
			return string(b), nil
		}
		root := findProjectRoot()
		path := filepath.Join(root, "templates", "docs", candidate+".md")
		b, err := os.ReadFile(path)
		if err == nil && len(strings.TrimSpace(string(b))) > 0 {
			return string(b), nil
		}
	}
	return "", fmt.Errorf("read doc template %s: file not found", name)
}

func templateNames(name string) []string {
	names := []string{name}
	if canonical := workflowdef.CanonicalTaskKey(name); canonical != name {
		names = append(names, canonical)
	}
	if legacy := workflowdef.ImplementationTaskKey(name); legacy != name {
		names = append(names, legacy)
	}
	return names
}

func GetAgentInstruction(role string) (string, error) {
	role = strings.TrimSuffix(role, ".md")
	if role == "" || strings.Contains(role, "..") || strings.ContainsAny(role, `/\`) {
		return "", fmt.Errorf("read agent instruction: invalid role %q", role)
	}
	return GetAgentInstructionFile(filepath.Join("configs", "agents", role+".md"))
}

// GetAgentInstructionFile 读取 configs/agents/ 下指定相对路径的指令文件，
// 并自动追加 configs/shared/writing.md。rel 必须落在 configs/agents/ 内，拒绝 ".."。
func GetAgentInstructionFile(rel string) (string, error) {
	rel = filepath.ToSlash(strings.TrimSpace(rel))
	if rel == "" || strings.Contains(rel, "..") {
		return "", fmt.Errorf("read agent instruction file: invalid path %q", rel)
	}
	if !strings.HasPrefix(rel, "configs/agents/") {
		return "", fmt.Errorf("read agent instruction file: must be under configs/agents/: %q", rel)
	}
	root := findProjectRoot()
	path := filepath.Join(root, filepath.FromSlash(rel))
	b, err := os.ReadFile(path)
	if err != nil {
		return "", fmt.Errorf("read agent instruction file %s: %w", rel, err)
	}

	inst := string(b)
	writingPath := filepath.Join(root, "configs", "shared", "writing.md")
	if wb, err := os.ReadFile(writingPath); err == nil {
		inst += "\n\n" + string(wb)
	}
	return inst, nil
}