package slurm

import (
	"encoding/json"
	"fmt"
	"io"
	"net/http"
)

// errorResponseFields is used to parse errors/warnings from a Slurm API error body.
type errorResponseFields struct {
	Errors   OpenapiErrors   `json:"errors,omitempty"`
	Warnings OpenapiWarnings `json:"warnings,omitempty"`
}

// SlurmAPIError represents a structured error returned by the Slurm REST API.
// It captures both the HTTP details and the parsed Slurm error array when available.
type SlurmAPIError struct {
	Response   *http.Response
	StatusCode int
	Errors     OpenapiErrors
	Warnings   OpenapiWarnings
	Message    string // raw body fallback when JSON parsing fails
}

func (e *SlurmAPIError) Error() string {
	if len(e.Errors) > 0 {
		first := e.Errors[0]
		detail := ""
		if first.Error != nil {
			detail = *first.Error
		} else if first.Description != nil {
			detail = *first.Description
		}
		if detail != "" {
			return fmt.Sprintf("%v %v: %d %s",
				e.Response.Request.Method, e.Response.Request.URL,
				e.StatusCode, detail)
		}
	}
	return fmt.Sprintf("%v %v: %d %s",
		e.Response.Request.Method, e.Response.Request.URL,
		e.StatusCode, e.Message)
}

// IsNotFound reports whether err is a SlurmAPIError with HTTP 404 status.
func IsNotFound(err error) bool {
	if apiErr, ok := err.(*SlurmAPIError); ok {
		return apiErr.StatusCode == http.StatusNotFound
	}
	return false
}

// CheckResponse checks the API response for errors. It returns nil if the
// response is a 2xx status code. For non-2xx codes, it reads the response
// body, attempts to parse structured Slurm errors, and returns a SlurmAPIError.
func CheckResponse(r *http.Response) error {
	if c := r.StatusCode; c >= 200 && c <= 299 {
		return nil
	}

	data, err := io.ReadAll(r.Body)
	if err != nil || len(data) == 0 {
		return &SlurmAPIError{
			Response:   r,
			StatusCode: r.StatusCode,
			Message:    r.Status,
		}
	}

	apiErr := &SlurmAPIError{
		Response:   r,
		StatusCode: r.StatusCode,
		Message:    string(data),
	}

	// Try to extract structured errors/warnings from JSON body.
	var fields errorResponseFields
	if json.Unmarshal(data, &fields) == nil {
		apiErr.Errors = fields.Errors
		apiErr.Warnings = fields.Warnings
	}

	return apiErr
}