package promptcompat

import (
	"encoding/json"
	"fmt"
	"strings"

	"ds2api/internal/toolcall"
)

func injectToolPrompt(messages []map[string]any, tools []any, policy ToolChoicePolicy) ([]map[string]any, []string) {
	if policy.IsNone() {
		return messages, nil
	}
	toolSchemas := make([]string, 0, len(tools))
	names := make([]string, 0, len(tools))
	isAllowed := func(name string) bool {
		if strings.TrimSpace(name) == "" {
			return false
		}
		if len(policy.Allowed) == 0 {
			return true
		}
		_, ok := policy.Allowed[name]
		return ok
	}

	for _, t := range tools {
		tool, ok := t.(map[string]any)
		if !ok {
			continue
		}
		name, desc, schema := toolcall.ExtractToolMeta(tool)
		name = strings.TrimSpace(name)
		if !isAllowed(name) {
			continue
		}
		names = append(names, name)
		if desc == "" {
			desc = "No description available"
		}
		b, _ := json.Marshal(schema)
		toolSchemas = append(toolSchemas, fmt.Sprintf("Tool: %s\nDescription: %s\nParameters: %s", name, desc, string(b)))
	}
	if len(toolSchemas) == 0 {
		return messages, names
	}
	toolPrompt := "You have access to these tools:\n\n" + strings.Join(toolSchemas, "\n\n") + "\n\n" + toolcall.BuildToolCallInstructions(names)
	if policy.Mode == ToolChoiceRequired {
		toolPrompt += "\n7) For this response, you MUST call at least one tool from the allowed list."
	}
	if policy.Mode == ToolChoiceForced && strings.TrimSpace(policy.ForcedName) != "" {
		toolPrompt += "\n7) For this response, you MUST call exactly this tool name: " + strings.TrimSpace(policy.ForcedName)
		toolPrompt += "\n8) Do not call any other tool."
	}

	for i := range messages {
		if messages[i]["role"] == "system" {
			old, _ := messages[i]["content"].(string)
			messages[i]["content"] = strings.TrimSpace(old + "\n\n" + toolPrompt)
			return messages, names
		}
	}
	messages = append([]map[string]any{{"role": "system", "content": toolPrompt}}, messages...)
	return messages, names
}