package healthcheck

import (
	"encoding/json"
	"fmt"
	"io"
	"os"
	"strings"
	"time"

	"github.com/briandowns/spinner"
	"github.com/fatih/color"
	"github.com/mattn/go-isatty"
)

const (
	// JSONOutput is used to specify the json output format
	JSONOutput = "json"
	// TableOutput is used to specify the table output format
	TableOutput = "table"
	// WideOutput is used to specify the wide output format
	WideOutput = "wide"
)

var (
	okStatus   = color.New(color.FgGreen, color.Bold).SprintFunc()("\u221A")  // √
	warnStatus = color.New(color.FgYellow, color.Bold).SprintFunc()("\u203C") // ‼
	failStatus = color.New(color.FgRed, color.Bold).SprintFunc()("\u00D7")    // ×
)

// RunChecks runs the checks that are part of hc
func RunChecks(wout io.Writer, werr io.Writer, hc Runner, output string) bool {
	if output == JSONOutput {
		return runChecksJSON(wout, werr, hc)
	}
	return runChecksTable(wout, hc)
}

func runChecksTable(wout io.Writer, hc Runner) bool {
	var lastCategory CategoryID
	spin := spinner.New(spinner.CharSets[9], 100*time.Millisecond)
	spin.Writer = wout

	prettyPrintResults := func(result *CheckResult) {
		if lastCategory != result.Category {
			if lastCategory != "" {
				fmt.Fprintln(wout)
			}

			fmt.Fprintln(wout, result.Category)
			fmt.Fprintln(wout, strings.Repeat("-", len(result.Category)))

			lastCategory = result.Category
		}

		spin.Stop()
		if result.Retry {
			if isatty.IsTerminal(os.Stdout.Fd()) {
				spin.Suffix = fmt.Sprintf(" %s", result.Err)
				spin.Color("bold") // this calls spin.Restart()
			}
			return
		}

		status := okStatus
		if result.Err != nil {
			status = failStatus
			if result.Warning {
				status = warnStatus
			}
		}

		fmt.Fprintf(wout, "%s %s\n", status, result.Description)
		if result.Err != nil {
			fmt.Fprintf(wout, "    %s\n", result.Err)
			if result.HintAnchor != "" {
				fmt.Fprintf(wout, "    see %s%s for hints\n", HintBaseURL, result.HintAnchor)
			}
		}
	}

	success := hc.RunChecks(prettyPrintResults)
	// this empty line separates final results from the checks list in the output
	fmt.Fprintln(wout, "")

	if !success {
		fmt.Fprintf(wout, "Status check results are %s\n", failStatus)
	} else {
		fmt.Fprintf(wout, "Status check results are %s\n", okStatus)
	}

	return success
}

type checkOutput struct {
	Success    bool             `json:"success"`
	Categories []*checkCategory `json:"categories"`
}

type checkCategory struct {
	Name   string   `json:"categoryName"`
	Checks []*check `json:"checks"`
}

// check is a user-facing version of `healthcheck.CheckResult`, for output via
// `linkerd check -o json`.
type check struct {
	Description string      `json:"description"`
	Hint        string      `json:"hint,omitempty"`
	Error       string      `json:"error,omitempty"`
	Result      checkResult `json:"result"`
}

type checkResult string

const (
	checkSuccess checkResult = "success"
	checkWarn    checkResult = "warning"
	checkErr     checkResult = "error"
)

func runChecksJSON(wout io.Writer, werr io.Writer, hc Runner) bool {
	var categories []*checkCategory

	collectJSONOutput := func(result *CheckResult) {
		categoryName := string(result.Category)
		if categories == nil || categories[len(categories)-1].Name != categoryName {
			categories = append(categories, &checkCategory{
				Name:   categoryName,
				Checks: []*check{},
			})
		}

		if !result.Retry {
			currentCategory := categories[len(categories)-1]
			// ignore checks that are going to be retried, we want only final results
			status := checkSuccess
			if result.Err != nil {
				status = checkErr
				if result.Warning {
					status = checkWarn
				}
			}

			currentCheck := &check{
				Description: result.Description,
				Result:      status,
			}

			if result.Err != nil {
				currentCheck.Error = result.Err.Error()

				if result.HintAnchor != "" {
					currentCheck.Hint = fmt.Sprintf("%s%s", HintBaseURL, result.HintAnchor)
				}
			}
			currentCategory.Checks = append(currentCategory.Checks, currentCheck)
		}
	}

	result := hc.RunChecks(collectJSONOutput)

	outputJSON := checkOutput{
		Success:    result,
		Categories: categories,
	}

	resultJSON, err := json.MarshalIndent(outputJSON, "", "  ")
	if err == nil {
		fmt.Fprintf(wout, "%s\n", string(resultJSON))
	} else {
		fmt.Fprintf(werr, "JSON serialization of the check result failed with %s", err)
	}
	return result
}