// Package main implements a tool for automatically updating component
// versions for use in the hack/* scripts.
//
// Files interacted with:
//  1. The source-of-truth file at hack/component-versions.json
//  2. Autogenerated script at hack/component-versions.sh
//
// USAGE:
//
// This is running on semi-auto basis where versions are being auto bumped via
// PRs sent to main. Semi-auto because if repo is missing 'owner' or 'repo' fields
// in the .json it will not be automatically bumped (it has no repo to look).
// This is intentional for components we dont want autobumped like this.
// The source-of-truth file is found in this repo @root/hack/component-versions.json
//
// ADD NEW/MODIFY COMPONENTS
//
//  1. Edit source-of-truth .json file
//     ! If a component is missing "owner" or "repo" it will not be auto-bumped
//  2. If new component was added:
//     - Edit the autogenerated text just below here 'versionsScriptTemplate'
//  3. Regenerate using Makefile - find target 'hack-generate-components'
package main

import (
	"context"
	"encoding/json"
	"fmt"
	"html/template"
	"os"
	"os/signal"
	"syscall"

	github "github.com/google/go-github/v68/github"
)

const (
	fileScript string = "component-versions.sh"
	fileJson   string = "component-versions.json"

	versionsScriptTemplate string = `#!/usr/bin/env bash

# AUTOGENERATED FILE - edit versions in ./component-versions.json.
# If you want to add/modify these components, please read the how-to steps in
# ./cmd/components/main.go.
# You can regenerate with "make hack-generate-components".

set_versions() {
	# Note: Kubernetes Version node image per Kind releases (full hash is suggested):
	# https://github.com/kubernetes-sigs/kind/releases
	kind_node_version={{.KindNode.Version}}

	# find source-of-truth in component-versions.json to add/modify components
	knative_serving_version="{{.Serving.Version}}"
	knative_eventing_version="{{.Eventing.Version}}"
	contour_version="{{.Contour.Version}}"
	tekton_version="{{.Tekton.Version}}"
	pac_version="{{.Pac.Version}}"
}
`
)

// Individual component info like for "Serving" or "Eventing"
// If you want to add new component, read the comment at the top of the file!
type Component struct {
	Version string `json:"version"`
	Owner   string `json:"owner,omitempty"`
	Repo    string `json:"repo,omitempty"`
}

// make iterable struct
type ComponentList map[string]*Component

func main() {
	// Set up context for possible signal inputs to not disrupt cleanup process.
	// This is not gonna do much for workflows since they finish and shutdown
	// but in case of local testing - dont leave left over resources on disk/RAM.
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()
	sigs := make(chan os.Signal, 1)
	signal.Notify(sigs, syscall.SIGINT, syscall.SIGTERM)
	go func() {
		<-sigs
		cancel()
		<-sigs
		os.Exit(130)
	}()

	getClient := func(token string) *github.Client {
		if token != "" {
			fmt.Println("client with token")
			return github.NewClient(nil).WithAuthToken(token)
		}
		return github.NewClient(nil)
	}
	client := getClient(os.Getenv("GITHUB_TOKEN"))

	// Read source-of-truth .json
	componentList, err := readVersions(fileJson)
	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}

	// update componentList in-situ
	updated, err := update(ctx, client, &componentList)
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to update %v\n", err)
		os.Exit(1)
	}

	if !updated {
		// nothing was updated, nothing to do
		fmt.Println("no newer versions found, re-generating .sh just in case")
		// regenerate .sh to keep up to date if changed
		err = writeScript(componentList, fileScript)
		if err != nil {
			err = fmt.Errorf("failed to re-generate script: %v", err)
			fmt.Fprintln(os.Stderr, err)
			os.Exit(1)
		}
		fmt.Println("all good")
		os.Exit(0)
	}

	if err := writeFiles(componentList, fileScript, fileJson); err != nil {
		err = fmt.Errorf("failed to write files: %v", err)
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}

	fmt.Println("files updated!")
}

// do the update for each repo defined
func update(ctx context.Context, client *github.Client, cl *ComponentList) (bool, error) {
	fmt.Println("Getting latest releases")
	updated := false
	for _, c := range *cl {
		if c.Owner == "" || c.Repo == "" {
			//skipping auto updates
			continue
		}

		newV, err := getLatestVersion(ctx, client, c.Owner, c.Repo)
		if err != nil {
			err = fmt.Errorf("error while getting latest v of %s/%s: %v", c.Owner, c.Repo, err)
			return false, err
		}

		if c.Version != newV {
			fmt.Printf("bump %v: %v --> %v\n", fmt.Sprintf("%s/%s", c.Owner, c.Repo), c.Version, newV)
			c.Version = newV
			updated = true
		}
	}
	return updated, nil
}

// read (unmarshal) component versions from .json
func readVersions(file string) (c ComponentList, err error) {
	fmt.Println("Reading versions from source-of-truth")
	data, err := os.ReadFile(file)
	if err != nil {
		return
	}
	err = json.Unmarshal(data, &c)
	if err != nil {
		return
	}
	return
}

// Overwrite the 'source of truth' file - .json and regenerate new script
// with new versions from 'v'.
// Arguments 'script' & 'json' are paths to files for autogenerated script and
// source (json) file respectively.
func writeFiles(cl ComponentList, script, json string) error {
	fmt.Print("Writing files")
	// write to json
	err := writeSource(cl, json)
	if err != nil {
		return fmt.Errorf("failed to write to json: %v", err)
	}
	// write to script file
	err = writeScript(cl, script)
	if err != nil {
		return fmt.Errorf("failed to generate script: %v", err)
	}
	return nil
}

// write to 'source of truth' .json with updated versions (if pulled latest)
func writeSource(cl ComponentList, file string) error {
	vB, err := json.MarshalIndent(cl, "", "	")
	if err != nil {
		return fmt.Errorf("cant Marshal versions: %v", err)
	}
	f, err := os.Create(file)
	if err != nil {
		return err
	}

	defer f.Close()

	_, err = f.Write(append(vB, '\n')) // append newline for reviewdog
	return err
}

// write the autogenerated script based on 'cl'
func writeScript(cl ComponentList, file string) error {
	tmpl, err := template.New("versions").Parse(versionsScriptTemplate)
	if err != nil {
		return err
	}
	f, err := os.Create(file)
	if err != nil {
		return err
	}
	defer f.Close()

	if err := tmpl.Execute(f, cl); err != nil {
		return err
	}
	return nil
}

// get latest version of owner/repo via GH API
func getLatestVersion(ctx context.Context, client *github.Client, owner string, repo string) (v string, err error) {
	rr, res, err := client.Repositories.GetLatestRelease(ctx, owner, repo)
	if err != nil {
		err = fmt.Errorf("error: request for latest %s release: %v", owner+"/"+repo, err)
		return
	}
	if res.StatusCode < 200 && res.StatusCode > 299 {
		err = fmt.Errorf("error: Return status code of request for latest %s release is %d", owner+"/"+repo, res.StatusCode)
		return
	}
	v = *rr.Name
	if v == "" {
		return "", fmt.Errorf("internal error: returned latest release name is empty for '%s'", repo)
	}
	return v, nil
}