// A Dagger module for building and deploying a Zola static website
//
// This module provides modular functions to:
// - Build the Zola website
// - Create a Docker image serving the site with nginx
// - Deploy to S3 (future)

package main

import (
	"context"
	"dagger/blog/internal/dagger"
	"fmt"
	"strings"
)

const (
	// Zola version to use for building
	ZolaImage = "ghcr.io/getzola/zola:v0.21.0"
	// Nginx version to use for serving
	NginxImage = "nginx:1.27-alpine3.20-slim"
	// Build output directory
	BuildOutputDir = "public"
	// Lychee version for link checking
	LycheeImage = "lycheeverse/lychee:0.22-alpine"
	// htmltest version for HTML validation
	HtmltestImage = "wjdp/htmltest:v0.17.0"
)

type Blog struct{}

// Build builds the Zola website and returns the public directory
//
// Args:
//   - source: The source directory containing the Zola site
//
// Returns:
//   - A Directory containing the built website
func (m *Blog) Build(
	ctx context.Context,
	// The source directory containing the Zola site
	// +defaultPath="/"
	// +ignore=[".git", ".dagger", "public"]
	source *dagger.Directory,
) *dagger.Directory {
	return dag.Container().
		From(ZolaImage).
		WithMountedDirectory("/site", source).
		WithWorkdir("/site").
		WithExec([]string{"zola", "build", "--output-dir", BuildOutputDir, "--minify"}).
		Directory(BuildOutputDir)
}

// prepareNginx prepares an nginx container with configuration
func (m *Blog) prepareNginx() *dagger.Container {
	nginxConfig := `server {
    listen 80;
    listen [::]:80;
    server_name _;

    root /usr/share/nginx/html;
    index index.html;

    # Enable gzip compression
    gzip on;
    gzip_vary on;
    gzip_min_length 1024;
    gzip_types text/plain text/css text/xml text/javascript application/javascript application/xml+rss application/json;

    location / {
        try_files $uri $uri/ =404;
    }

    # Cache static assets
    location ~* \.(jpg|jpeg|png|gif|ico|css|js|svg|woff|woff2|ttf|eot)$ {
        expires 1y;
        add_header Cache-Control "public, immutable";
    }
}`

	return dag.Container().
		From(NginxImage).
		WithNewFile("/etc/nginx/conf.d/default.conf", nginxConfig).
		WithExposedPort(80)
}

// BuildContainer creates a Docker container image with nginx serving the built website
//
// Args:
//   - source: The source directory containing the Zola site
//
// Returns:
//   - A Container ready to serve the website
func (m *Blog) BuildContainer(
	ctx context.Context,
	// The source directory containing the Zola site
	// +defaultPath="/"
	// +ignore=[".git", ".dagger", "public"]
	source *dagger.Directory,
) *dagger.Container {
	builtSite := m.Build(ctx, source)
	nginxContainer := m.prepareNginx()

	return nginxContainer.WithDirectory("/usr/share/nginx/html", builtSite)
}

// getDefaultTag returns a tag based on the latest git commit date
func (m *Blog) getDefaultTag(
	ctx context.Context,
	source *dagger.Directory,
) (string, error) {
	// Get the commit date in YYYYMMDDHHMMSS format
	output, err := dag.Container().
		From("alpine/git:latest").
		WithMountedDirectory("/repo", source).
		WithWorkdir("/repo").
		WithExec([]string{"git", "log", "-1", "--format=%cd", "--date=format:%Y%m%d%H%M%S"}).
		Stdout(ctx)

	if err != nil {
		return "", err
	}

	return strings.TrimSpace(output), nil
}

// Publish publishes the container to a registry
//
// Args:
//   - source: The source directory containing the Zola site
//   - registry: The registry address (e.g., "ghcr.io/username/blog")
//   - tag: The tag to use (defaults to git commit date in YYYYMMDDHHMMSS format)
//
// Returns:
//   - The published image reference
func (m *Blog) Publish(
	ctx context.Context,
	// The source directory containing the Zola site
	// +defaultPath="/"
	// +ignore=[".git", ".dagger", "public"]
	source *dagger.Directory,
	// The registry address
	registry string,
	// +optional
	tag string,
) (string, error) {
	if tag == "" {
		defaultTag, err := m.getDefaultTag(ctx, source)
		if err != nil {
			return "", err
		}
		tag = defaultTag
	}

	container := m.BuildContainer(ctx, source)
	address := registry + ":" + tag

	return container.Publish(ctx, address)
}

// checkLinks validates all links in the built site
func (m *Blog) checkLinks(
	ctx context.Context,
	builtSite *dagger.Directory,
) error {
	_, err := dag.Container().
		From(LycheeImage).
		WithMountedDirectory("/site", builtSite).
		WithWorkdir("/site").
		WithExec([]string{
			"lychee",
			"--base-url", "https://enoent.fr",
			"--remap", "https://enoent\\.fr/ file:///site/",
			"--offline",
			"--no-progress",
			"/site",
		}).
		Sync(ctx)

	return err
}

// checkHTML validates HTML structure
func (m *Blog) checkHTML(
	ctx context.Context,
	builtSite *dagger.Directory,
) error {
	// htmltest configuration
	// Enable comprehensive HTML validation
	htmltestConfig := `DirectoryPath: /site
CheckDoctype: true
CheckAnchors: true
CheckLinks: true
CheckImages: true
CheckScripts: true
CheckFavicon: false
CheckMetaRefresh: true
CheckMetaDescription: true
EnforceHTTPS: false
IgnoreInternalEmptyHash: true
IgnoreDirectoryMissingTrailingSlash: true
CheckExternal: false
IgnoreURLs:
  - "^https://enoent\\.fr/"`

	_, err := dag.Container().
		From(HtmltestImage).
		WithMountedDirectory("/site", builtSite).
		WithWorkdir("/test").
		WithNewFile(".htmltest.yml", htmltestConfig).
		WithExec([]string{"htmltest"}).
		Sync(ctx)

	return err
}

// Check runs all quality checks on the built site
//
// Args:
//   - source: The source directory containing the Zola site
//
// Returns:
//   - An error if any check fails
func (m *Blog) Check(
	ctx context.Context,
	// The source directory containing the Zola site
	// +defaultPath="/"
	// +ignore=[".git", ".dagger", "public"]
	source *dagger.Directory,
) error {
	// Build the site first
	builtSite := m.Build(ctx, source)

	type checkResult struct {
		name string
		err  error
	}

	checks := []struct {
		name string
		fn   func(context.Context, *dagger.Directory) error
	}{
		{"Link Check", m.checkLinks},
		{"HTML Validation", m.checkHTML},
	}

	results := make(chan checkResult, len(checks))

	for _, check := range checks {
		check := check
		go func() {
			results <- checkResult{
				name: check.name,
				err:  check.fn(ctx, builtSite),
			}
		}()
	}

	// Collect results
	var failures []string
	for i := 0; i < len(checks); i++ {
		result := <-results
		if result.err != nil {
			failures = append(failures, fmt.Sprintf("%s failed: %v", result.name, result.err))
		}
	}

	// Return combined error if any checks failed
	if len(failures) > 0 {
		return fmt.Errorf("checks failed:\n%s", strings.Join(failures, "\n"))
	}

	return nil
}