package llm

import (
	"fmt"
	"os"
)

const (
	PromptTypeFormatting = "formatting"
)

// LoadDefaultPrompt reads the built-in default prompt for the given type.
func LoadDefaultPrompt(promptType string) (string, error) {
	var filename string
	switch promptType {
	case PromptTypeFormatting:
		filename = "prompts/formatting.txt"
	default:
		return "", fmt.Errorf("unknown prompt type: %s", promptType)
	}

	data, err := os.ReadFile(filename)
	if err != nil {
		return "", fmt.Errorf("reading default prompt %s: %w", filename, err)
	}
	return string(data), nil
}

// BuildFormatMessage builds the user message for the formatting pass.
// If userInstructions is non-empty, it wraps the markdown with the prompt instructions tags.
func BuildFormatMessage(markdown string, userInstructions string) string {
	prefix := "Here is the markdown text from a PDF form. Clean up formatting anomalies only — return the ENTIRE document with no sections omitted. Do not summarize, rewrite, or answer the form.\n\n"
	if userInstructions != "" {
		prefix += fmt.Sprintf("<!-- PROMPT_INSTRUCTIONS -->\n%s\n<!-- END_INSTRUCTIONS -->\n\n", userInstructions)
	}
	prefix += "## Markdown to clean:\n"
	return prefix + markdown
}

// FormatResponse extracts clean markdown from the LLM response.
// Strips code fences if present.
func FormatResponse(response string) string {
	// Strip markdown code fences if present
	const open = "```"
	const close = "```"
	const openMd = "```markdown"
	const openMdNL = "```md"

	start := 0
	if len(response) > len(openMdNL) && response[:len(openMdNL)] == openMdNL {
		// Find newline after ```md
		for i := len(openMdNL); i < len(response); i++ {
			if response[i] == '\n' {
				start = i + 1
				break
			}
		}
	} else if len(response) > len(openMd) && response[:len(openMd)] == openMd {
		for i := len(openMd); i < len(response); i++ {
			if response[i] == '\n' {
				start = i + 1
				break
			}
		}
	} else if len(response) > len(open) && response[:len(open)] == open {
		for i := len(open); i < len(response); i++ {
			if response[i] == '\n' {
				start = i + 1
				break
			}
		}
	}

	if start > 0 {
		// Find closing fence
		idx := len(response) - len(close)
		for i := start; i <= idx; i++ {
			if response[i:i+len(close)] == close {
				return response[start:i]
			}
		}
		return response[start:]
	}
	return response
}

// HasOpenAIKey checks if the OpenAI API key is configured.
func HasOpenAIKey() bool {
	return os.Getenv("OPENAI_API_KEY") != ""
}