/*
Copyright 2020 The Flux authors

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package install

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"os"
	"path"
	"strings"
	"time"

	securejoin "github.com/cyphar/filepath-securejoin"
	"github.com/hashicorp/go-cleanhttp"

	"github.com/fluxcd/flux2/v2/pkg/manifestgen"
)

// Generate returns the install manifests as a multi-doc YAML.
// The manifests are built from a GitHub release or from a
// Kustomize overlay if the supplied Options.BaseURL is a local path.
// The manifestsBase should be set to an empty string when Generate is
// called by consumers that don't embed the manifests.
func Generate(options Options, manifestsBase string) (*manifestgen.Manifest, error) {
	ctx, cancel := context.WithTimeout(context.Background(), options.Timeout)
	defer cancel()

	var err error

	output, err := securejoin.SecureJoin(manifestsBase, options.ManifestFile)
	if err != nil {
		return nil, err
	}

	if !strings.HasPrefix(options.BaseURL, "http") {
		if err := build(options.BaseURL, output); err != nil {
			return nil, err
		}
	} else {
		// download the manifests base from GitHub
		if manifestsBase == "" {
			manifestsBase, err = manifestgen.MkdirTempAbs("", options.Namespace)
			if err != nil {
				return nil, fmt.Errorf("temp dir error: %w", err)
			}
			defer os.RemoveAll(manifestsBase)
			output, err = securejoin.SecureJoin(manifestsBase, options.ManifestFile)
			if err != nil {
				return nil, err
			}
			if err := fetch(ctx, options.BaseURL, options.Version, manifestsBase); err != nil {
				return nil, err
			}
		}

		if err := generate(manifestsBase, options); err != nil {
			return nil, err
		}

		if err := build(manifestsBase, output); err != nil {
			return nil, err
		}
	}

	content, err := os.ReadFile(output)
	if err != nil {
		return nil, err
	}

	return &manifestgen.Manifest{
		Path:    path.Join(options.TargetPath, options.Namespace, options.ManifestFile),
		Content: fmt.Sprintf("%s\n%s", GetGenWarning(options), string(content)),
	}, nil
}

// GetLatestVersion calls the GitHub API and returns the latest released version.
func GetLatestVersion() (string, error) {
	ghURL := "https://api.github.com/repos/fluxcd/flux2/releases/latest"
	c := cleanhttp.DefaultClient()
	c.Timeout = 15 * time.Second

	res, err := c.Get(ghURL)
	if err != nil {
		return "", fmt.Errorf("GitHub API call failed: %w", err)
	}

	if res.Body != nil {
		defer res.Body.Close()
	}

	type meta struct {
		Tag string `json:"tag_name"`
	}
	var m meta
	if err := json.NewDecoder(res.Body).Decode(&m); err != nil {
		return "", fmt.Errorf("decoding GitHub API response failed: %w", err)
	}

	return m.Tag, err
}

// ExistingVersion calls the GitHub API to confirm the given version does exist.
func ExistingVersion(version string) (bool, error) {
	if !strings.HasPrefix(version, "v") {
		version = "v" + version
	}

	ghURL := fmt.Sprintf("https://api.github.com/repos/fluxcd/flux2/releases/tags/%s", version)
	c := cleanhttp.DefaultClient()
	c.Timeout = 15 * time.Second

	res, err := c.Get(ghURL)
	if err != nil {
		return false, fmt.Errorf("GitHub API call failed: %w", err)
	}

	if res.Body != nil {
		defer res.Body.Close()
	}

	switch res.StatusCode {
	case http.StatusOK:
		return true, nil
	case http.StatusNotFound:
		return false, nil
	default:
		return false, fmt.Errorf("GitHub API returned an unexpected status code (%d)", res.StatusCode)
	}
}

// GetGenWarning generates a consistent generation warning in the install and bootstrap case in the following format:
// # This manifest was generated by flux. DO NOT EDIT.
// # Flux version: v0.21.1
// # Components: source-controller,kustomize-controller,helm-controller,notification-controller,image-reflector-controller,image-automation-controller
func GetGenWarning(options Options) string {
	return fmt.Sprintf("---\n%s\n# Flux Version: %s\n# Components: %s", manifestgen.GenWarning, options.Version, strings.Join(options.Components, ","))
}