//go:build mage

package main

import (
	"fmt"
	"io"
	"log/slog"
	"os"
	"path/filepath"
	"strings"

	"github.com/go-git/go-git/v5"
	"github.com/go-git/go-git/v5/plumbing"
	"github.com/goccy/go-yaml"
)

type projectsConfig struct {
	Projects []project `yaml:"projects"`
}

type project struct {
	Name              string `yaml:"name"`
	RepositoryURL     string `yaml:"repository_url"`
	Commit            string `yaml:"commit"`
	Tag               string `yaml:"tag"`
	Branch            string `yaml:"branch"`
	GitReference      string `yaml:"git_reference"`
	DocumentationRoot string `yaml:"documentation_root"`
}

var (
	configFile        = "./flow/nanoc.yaml"
	projectsDirectory = "./flow/content/projects"
)

func Projects() error {
	logger := slog.New(slog.NewTextHandler(os.Stdout, nil))
	slog.SetDefault(logger)

	projects, err := parseProjectsConfig()
	if err != nil {
		return fmt.Errorf("unable to parse the projects configuration; %w", err)
	}

	for _, project := range projects.Projects {
		clonedDirectory, err := cloneProject(project)
		if err != nil {
			return fmt.Errorf("unable to clone %q; %w", project.Name, err)
		}

		documentationDir := filepath.Join(clonedDirectory, project.DocumentationRoot)

		if err := copyDocumentation(documentationDir, project.Name); err != nil {
			return fmt.Errorf("unable to copy the documentation from %q; %w", project.Name, err)
		}
	}

	return nil
}

func parseProjectsConfig() (projectsConfig, error) {
	slog.Info("Parsing configuration.", "config file", configFile)

	var config projectsConfig

	data, err := os.ReadFile(configFile)
	if err != nil {
		return config, fmt.Errorf("unable to read %q; %w", configFile, err)
	}

	if err := yaml.Unmarshal(data, &config); err != nil {
		return config, fmt.Errorf("unable to Unmarshal the configuration; %w", err)
	}

	slog.Info("Configuration parsed successfully.")

	return config, nil
}

func cloneProject(p project) (string, error) {
	slog.Info("Cloning the project repository.", "repository", p.RepositoryURL)
	var (
		reference    plumbing.ReferenceName
		singleBranch bool
		depth        int
	)

	if p.Tag != "" {
		reference = plumbing.NewTagReferenceName(p.Tag)
		singleBranch = false
		depth = 1
	} else if p.Branch != "" {
		reference = plumbing.NewBranchReferenceName(p.Branch)
		singleBranch = true
		depth = 1
	} else {
		reference = plumbing.Main
		singleBranch = false
		depth = 0
	}

	cloneDir, err := os.MkdirTemp("", p.Name)
	if err != nil {
		return "", fmt.Errorf("unable to create the temporary clone directory; %w", err)
	}

	options := git.CloneOptions{
		URL:           p.RepositoryURL,
		Progress:      nil,
		ReferenceName: reference,
		SingleBranch:  singleBranch,
		Depth:         depth,
	}

	repository, err := git.PlainClone(cloneDir, false, &options)
	if err != nil {
		return "", fmt.Errorf("unable to clone the repository; %w", err)
	}

	if p.Commit == "" {
		return cloneDir, nil
	}

	worktree, err := repository.Worktree()
	if err != nil {
		return "", fmt.Errorf("unable to retrieve the work tree; %w", err)
	}

	checkoutOptions := git.CheckoutOptions{
		Hash:   plumbing.NewHash(p.Commit),
		Create: false,
	}

	if err := worktree.Checkout(&checkoutOptions); err != nil {
		return "", fmt.Errorf("unable to checkout %q; %w", p.Commit, err)
	}

	slog.Info("Project cloned successfully.")

	return cloneDir, nil
}

func copyDocumentation(inputDirectory, projectName string) error {
	outputDirectory := filepath.Join(projectsDirectory, projectName)

	slog.Info("Copying documentation.", "project", projectName, "source", inputDirectory, "destination", outputDirectory)

	defer os.RemoveAll(inputDirectory)

	files, err := os.ReadDir(inputDirectory)
	if err != nil {
		return fmt.Errorf("unable to read files from %q; %w", inputDirectory, err)
	}

	if len(files) == 0 {
		return nil
	}


	if err := os.MkdirAll(outputDirectory, 0o750); err != nil {
		return fmt.Errorf("unable to create %q; %w", outputDirectory, err)
	}

	for _, file := range files {
		if file.IsDir() || !strings.HasSuffix(file.Name(), ".asciidoc") {
			continue
		}

		inputPath := filepath.Join(inputDirectory, file.Name())
		outputPath := filepath.Join(projectsDirectory, projectName, file.Name())

		err := func() error {
			inputFile, err := os.Open(inputPath)
			if err != nil {
				return fmt.Errorf("unable to open %q; %w", inputPath, err)
			}
			defer inputFile.Close()

			outputFile, err := os.Create(outputPath)
			if err != nil {
				return fmt.Errorf("unable to create %q; %w", outputPath, err)
			}
			defer outputFile.Close()

			if _, err := io.Copy(outputFile, inputFile); err != nil {
				return fmt.Errorf(
					"unable to copy the contents from %q to %q; %w",
					inputPath,
					outputPath,
					err,
				)
			}

			return nil
		}()
		if err != nil {
			return err
		}
	}

	slog.Info("Documentation copied successfully.")

	return nil
}