package server

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

	"github.com/daniel/cursor-adapter/internal/types"
)

// cwdPatterns matches the most common ways callers (Claude Code, opencode,
// Cursor CLI itself, custom clients) advertise their host working
// directory inside the prompt.
//
// Patterns must capture an absolute path in group 1.
var cwdPatterns = []*regexp.Regexp{
	// Claude Code style:
	//   <env>
	//   Working directory: /Users/x/proj
	//   Is directory a git repo: Yes
	//   ...
	//   </env>
	regexp.MustCompile(`(?si)<env>.*?working directory:\s*(\S+)`),

	// Generic <cwd>...</cwd> wrapper.
	regexp.MustCompile(`(?i)<cwd>\s*([^<\s][^<]*?)\s*</cwd>`),

	// "Working directory: /abs/path" on its own line.
	regexp.MustCompile(`(?im)^\s*working directory:\s*(/[^\s<>]+)\s*$`),

	// "Current working directory is /abs/path" / "current working directory: /abs/path"
	regexp.MustCompile(`(?i)current working directory(?: is)?[:\s]+(/[^\s<>]+)`),

	// Loose "cwd: /abs/path" / "cwd=/abs/path".
	regexp.MustCompile(`(?i)\bcwd\s*[:=]\s*(/[^\s<>]+)`),
}

// detectCallerWorkspace returns the first absolute, host-resident directory
// it can extract from corpus. It rejects:
//   - non-absolute paths (e.g. "src/")
//   - paths that don't exist on the host (e.g. "/sessions/..." sandbox
//     paths sent by Claude Desktop's Cowork VM)
//   - paths that point to a file rather than a directory
//
// Returning "" simply means "no usable workspace hint found", and callers
// should fall back to config defaults.
func detectCallerWorkspace(corpus string) string {
	for _, p := range cwdPatterns {
		m := p.FindStringSubmatch(corpus)
		if len(m) < 2 {
			continue
		}
		cand := strings.TrimSpace(m[1])
		// Strip trailing punctuation that often follows a path in prose.
		cand = strings.TrimRight(cand, `.,;:"'`+"`)>")
		if cand == "" || !filepath.IsAbs(cand) {
			continue
		}
		info, err := os.Stat(cand)
		if err != nil || !info.IsDir() {
			continue
		}
		return cand
	}
	return ""
}

// detectAnthropicCwd scans an Anthropic Messages request for a workspace
// hint. It walks system blocks first (Claude Code / opencode usually put
// the <env> block there), then user/assistant text blocks (some clients
// embed it as <system-reminder> inside the first user message).
func detectAnthropicCwd(req types.AnthropicMessagesRequest) string {
	var sb strings.Builder
	for _, b := range req.System {
		if b.Type == "text" && b.Text != "" {
			sb.WriteString(b.Text)
			sb.WriteByte('\n')
		}
	}
	for _, m := range req.Messages {
		for _, b := range m.Content {
			if b.Type == "text" && b.Text != "" {
				sb.WriteString(b.Text)
				sb.WriteByte('\n')
			}
		}
	}
	return detectCallerWorkspace(sb.String())
}

// detectOpenAICwd scans an OpenAI-style chat completion request for a
// workspace hint, including system messages (which the brain prompt
// builder otherwise drops).
func detectOpenAICwd(req types.ChatCompletionRequest) string {
	var sb strings.Builder
	for _, m := range req.Messages {
		sb.WriteString(string(m.Content))
		sb.WriteByte('\n')
	}
	return detectCallerWorkspace(sb.String())
}