package woodpecker

import (
	"encoding/json"
	"fmt"
)

// APIError represents a failure returned by the Woodpecker API or an
// unrecoverable error while communicating with it. The Status field is an
// HTTP status code when the failure came from the API, or 500 for transport
// and decoding errors, mirroring the behaviour of the original client.
type APIError struct {
	Status  int
	Message string
}

func (e *APIError) Error() string {
	if e.Message == "" {
		return fmt.Sprintf("woodpecker api error (status %d)", e.Status)
	}
	return fmt.Sprintf("woodpecker api error (status %d): %s", e.Status, e.Message)
}

// errorContext is the structured payload returned to the MCP client when a
// tool call fails. The shape is kept identical to the original TypeScript
// implementation so existing MCP clients see the same output.
type errorContext struct {
	Description string   `json:"description"`
	Suggestions []string `json:"suggestions"`
	Error       string   `json:"error"`
}

// ToContext renders a client-facing error context for the given operation.
// The status code drives both the description and the suggested next steps.
func (e *APIError) ToContext(context string) string {
	description := "Request failed for " + context
	if e.Message != "" {
		description += ": " + e.Message
	}
	ctx := errorContext{
		Description: description,
		Suggestions: []string{
			"Check your network connection",
			"Verify the Woodpecker CI server URL is correct",
			"Try again in a few moments",
		},
		Error: "UNKNOWN_ERROR",
	}
	switch e.Status {
	case 401:
		ctx = errorContext{
			Description: "Authentication failed for " + context,
			Suggestions: []string{
				"Check that your WOODPECKER_TOKEN environment variable is set correctly",
				"Verify the token has not expired",
				"Ensure the token has sufficient permissions",
			},
			Error: "AUTH_ERROR",
		}
	case 403:
		ctx = errorContext{
			Description: "Access denied for " + context,
			Suggestions: []string{
				"Check that you have permission to access this resource",
				"Verify the repository/pipeline exists and is accessible",
				"Contact your Woodpecker CI administrator if needed",
			},
			Error: "PERMISSION_ERROR",
		}
	case 404:
		ctx = errorContext{
			Description: "Resource not found for " + context,
			Suggestions: []string{
				"Double-check the repository name, pipeline number, or step ID",
				"Verify the resource exists and hasn't been deleted",
			},
			Error: "NOT_FOUND",
		}
	case 429:
		ctx = errorContext{
			Description: "Rate limit exceeded for " + context,
			Suggestions: []string{
				"Wait a moment before retrying",
				"Consider reducing the frequency of requests",
			},
			Error: "RATE_LIMIT",
		}
	case 500, 502, 503, 504:
		ctx = errorContext{
			Description: "Woodpecker CI server error for " + context,
			Suggestions: []string{
				"Try again in a few moments",
				"Check Woodpecker CI server status",
				"Contact your administrator if the issue persists",
			},
			Error: "SERVER_ERROR",
		}
	}

	// Marshalling a plain struct never fails; ignore the error defensively.
	b, _ := json.Marshal(ctx)
	return string(b)
}