package main

import (
	"fmt"
	"io"
	"log"
	"log/slog"
	"net/url"
	"os"
	"path"
	"slices"

	"website/internal/config"

	cp "github.com/otiai10/copy"
	"github.com/pkg/errors"
)

func mkdirp(dirs ...string) error {
	return os.MkdirAll(path.Join(dirs...), 0755)
}

func outputToFile(output io.Reader, filename ...string) error {
	file, err := os.OpenFile(path.Join(filename...), os.O_WRONLY|os.O_CREATE, 0644)
	if err != nil {
		return errors.WithMessage(err, "could not open output file")
	}
	defer file.Close()

	if _, err := file.ReadFrom(output); err != nil {
		return errors.WithMessage(err, "could not write output file")
	}
	return nil
}

func build(outDir string, config config.Config) error {
	privateDir := path.Join(outDir, "private")
	if err := mkdirp(privateDir); err != nil {
		return errors.WithMessage(err, "could not create private directory")
	}
	publicDir := path.Join(outDir, "public")
	if err := mkdirp(publicDir); err != nil {
		return errors.WithMessage(err, "could not create public directory")
	}

	err := cp.Copy("static", publicDir, cp.Options{
		PreserveTimes:     true,
		PermissionControl: cp.AddPermission(0755),
	})
	if err != nil {
		log.Panic(errors.Errorf("could not copy static files: %v", err))
	}

	if err := mkdirp(publicDir, "post"); err != nil {
		return errors.WithMessage(err, "could not create post output directory")
	}
	slog.Debug("reading posts")
	posts, tags, err := readPosts("content", "post", publicDir)
	if err != nil {
		return err
	}

	for _, post := range posts {
		if err := mkdirp(publicDir, "post", post.Basename); err != nil {
			return errors.WithMessage(err, "could not create directory for post")
		}
		slog.Debug("rendering post", "post", post.Basename)
		output, err := renderPost(post, config)
		if err != nil {
			return errors.WithMessagef(err, "could not render post %s", post.Input)
		}
		if err := outputToFile(output, post.Output); err != nil {
			return err
		}
	}

	if err := mkdirp(publicDir, "tags"); err != nil {
		return errors.WithMessage(err, "could not create directory for tags")
	}
	slog.Debug("rendering tags list")
	output, err := renderTags(tags, config, "/tags")
	if err != nil {
		return errors.WithMessage(err, "could not render tags")
	}
	if err := outputToFile(output, publicDir, "tags", "index.html"); err != nil {
		return err
	}

	for _, tag := range tags.ToSlice() {
		matchingPosts := []Post{}
		for _, post := range posts {
			if slices.Contains(post.Taxonomies.Tags, tag) {
				matchingPosts = append(matchingPosts, post)
			}
		}
		if err := mkdirp(publicDir, "tags", tag); err != nil {
			return errors.WithMessage(err, "could not create directory")
		}
		slog.Debug("rendering tags page", "tag", tag)
		output, err := renderListPage(tag, config, matchingPosts, "/tags/"+tag)
		if err != nil {
			return errors.WithMessage(err, "could not render tag page")
		}
		if err := outputToFile(output, publicDir, "tags", tag, "index.html"); err != nil {
			return err
		}

		slog.Debug("rendering tags feed", "tag", tag)
		output, err = renderFeed(fmt.Sprintf("%s - %s", config.Title, tag), config, matchingPosts, tag)
		if err != nil {
			return errors.WithMessage(err, "could not render tag feed page")
		}
		if err := outputToFile(output, publicDir, "tags", tag, "atom.xml"); err != nil {
			return err
		}
	}

	slog.Debug("rendering list page")
	listPage, err := renderListPage("", config, posts, "/post")
	if err != nil {
		return errors.WithMessage(err, "could not render list page")
	}
	if err := outputToFile(listPage, publicDir, "post", "index.html"); err != nil {
		return err
	}

	slog.Debug("rendering feed")
	feed, err := renderFeed(config.Title, config, posts, "feed")
	if err != nil {
		return errors.WithMessage(err, "could not render feed")
	}
	if err := outputToFile(feed, publicDir, "atom.xml"); err != nil {
		return err
	}

	slog.Debug("rendering feed styles")
	feedStyles, err := renderFeedStyles()
	if err != nil {
		return errors.WithMessage(err, "could not render feed styles")
	}
	if err := outputToFile(feedStyles, publicDir, "feed-styles.xsl"); err != nil {
		return err
	}

	slog.Debug("rendering homepage")
	homePage, err := renderHomepage(config, posts, "/")
	if err != nil {
		return errors.WithMessage(err, "could not render homepage")
	}
	if err := outputToFile(homePage, publicDir, "index.html"); err != nil {
		return err
	}

	slog.Debug("rendering 404 page")
	notFound, err := render404(config, "/404.html")
	if err != nil {
		return errors.WithMessage(err, "could not render 404 page")
	}
	if err := outputToFile(notFound, privateDir, "404.html"); err != nil {
		return err
	}

	return nil
}

type IOConfig struct {
	Source      string `conf:"default:.,short:s"`
	Destination string `conf:"default:website,short:d"`
	BaseURL     config.URL
}

func buildSite(ioConfig IOConfig) error {
	config, err := config.GetConfig()
	if err != nil {
		log.Panic(errors.Errorf("could not get config: %v", err))
	}

	if ioConfig.BaseURL.URL != nil {
		config.BaseURL.URL, err = url.Parse(ioConfig.BaseURL.String())
		if err != nil {
			log.Panic(errors.Errorf("highly unlikely: %v", err))
		}
	}

	err = os.RemoveAll(ioConfig.Destination)
	if err != nil {
		log.Panic(errors.Errorf("could not remove public directory: %v", err))
	}

	if err := build(ioConfig.Destination, *config); err != nil {
		return err
	}

	slog.Debug("done")
	return nil
}