package usecase

import (
	"context"
	"errors"
	"fmt"
	"strings"

	"gitea.maximumdirect.net/eric/promptkit/internal/domain"
	"gitea.maximumdirect.net/eric/promptkit/internal/llm"
)

type OutputRepairer interface {
	Repair(ctx context.Context, req RepairRequest) (*domain.GenerateResponse, error)
}

type RepairRequest struct {
	PreviousOutput   string
	ValidationErrors []string
	SessionID        string
	Target           domain.ExecutionTarget
	TargetPresence   domain.ExecutionTargetPresence
	StructuredOutput *domain.StructuredOutputSpec
	Attempt          int
	MaxAttempts      int
	Mode             domain.ValidationMode
}

type defaultOutputRepairer struct {
	llm llm.Client
}

func NewDefaultOutputRepairer(llmClient llm.Client) OutputRepairer {
	return &defaultOutputRepairer{llm: llmClient}
}

func (r *defaultOutputRepairer) Repair(ctx context.Context, req RepairRequest) (*domain.GenerateResponse, error) {
	if r.llm == nil {
		return nil, errors.New("llm client is required for repair")
	}

	errs := "(none provided)"
	if len(req.ValidationErrors) > 0 {
		errs = strings.Join(req.ValidationErrors, "\n")
	}

	prompt := domain.RenderedPrompt{
		Messages: []domain.RenderedMessage{
			{
				Role:    "system",
				Content: "You repair invalid JSON output. Return only corrected JSON. Do not include explanations or markdown code fences.",
			},
			{
				Role: "user",
				Content: fmt.Sprintf(
					"Repair attempt %d of %d for validation mode %s.\n\nValidation errors:\n%s\n\nPrevious output:\n%s\n\nReturn only corrected JSON.",
					req.Attempt,
					req.MaxAttempts,
					req.Mode,
					errs,
					req.PreviousOutput,
				),
			},
		},
	}

	resp, err := r.llm.Generate(ctx, newGenerationRequest(
		prompt,
		req.SessionID,
		req.Target,
		req.TargetPresence,
		req.StructuredOutput,
	))
	if err != nil {
		return nil, err
	}
	if resp == nil {
		return nil, errors.New("repair llm returned nil response")
	}

	return resp, nil
}