package crawl

import (
	"crypto/sha256"
	"encoding/hex"
	"strings"

	"git.golem15.com/golem15/sm-seo-plugin/classes"
	"git.golem15.com/golem15/sm-seo-plugin/models"
	"git.golem15.com/golem15/summercms/modules/pact"
)

// The SEO tools an issue may name (pier prefixes them with seo_).
const (
	ToolSetURLSEO      = "seo_set_url_seo"
	ToolUpdateRobots   = "seo_update_robots"
	ToolCreateRedirect = "seo_create_redirect"
	ToolUpdatePage     = "seo_update_page"
	ToolCreatePage     = "seo_create_page"
	ToolUpdateSettings = "seo_update_settings"
	// ToolSitemapSettings is the sitemap plugin's settings tool, which
	// edits its Additional addresses.
	ToolSitemapSettings = "sitemap_update_settings"
)

// Record is the CMS record behind a crawled page: its content type, id
// and locale, the descriptor facts the checks compare the page with
// (title, word count, headings, images, the highest heading level) and the
// fixing tools its type names (pact.ContentDescriptor.Tools).
type Record struct {
	Type       string
	ID         string
	Locale     string
	Title      string
	Words      *int
	Headings   []pact.ContentHeading
	Images     []pact.ContentImage
	TopHeading int
	// Links are the record's CMS-known links: the address of its primary
	// parent, which the page's breadcrumb trail links to.
	Links []string
	Tools map[string]string
	// CustomJSONLD is true when the record's SEO tab stores custom JSON-LD.
	CustomJSONLD bool
}

// tool returns the record's tool for the first operation of ops it
// names, "" when it names none.
func (r *Record) tool(ops ...string) string {
	if r == nil {
		return ""
	}
	for _, op := range ops {
		if t := strings.TrimSpace(r.Tools[op]); t != "" {
			return t
		}
	}
	return ""
}

// hasHeading reports whether the record's own headings hold one of level
// (any level when level is 0) whose text is text (any text when empty).
func (r *Record) hasHeading(level int, text string) bool {
	if r == nil {
		return false
	}
	for _, h := range r.Headings {
		if level != 0 && h.Level != level {
			continue
		}
		if text == "" || normal(h.Text) == normal(text) {
			return true
		}
	}
	return false
}

// Finding is one problem a check found on a page, before it is stored:
// the kind, the address and locale, the details of the kind, and how it
// is fixed (P33-38). Tool is a fixed CMS tool (seo_*); Content lists the
// record operations (pact.ContentTool*) that fix a finding inside the
// record's own content, tried in order; What names the template element
// when it is fixed in code.
type Finding struct {
	Kind    string
	URL     string
	Locale  string
	Details map[string]any
	Tool    string
	Content []string
	Record  *Record
	What    string
	// Check tells the two content_js findings apart (cms, rendered).
	Check string
}

// Route applies P33-38: a finding inside the record's own content names
// the record type's fitting tool (H1 findings prefer Tools[headings],
// other content findings Tools[edit]); else a fixed CMS tool; else fix
// code with the template element in details.what. Every finding gets one
// of the two.
func Route(f Finding) (fix, tool, what string) {
	if len(f.Content) > 0 {
		if t := f.Record.tool(f.Content...); t != "" {
			return models.FixTool, t, ""
		}
	}
	if f.Tool != "" {
		return models.FixTool, f.Tool, ""
	}
	what = f.What
	if what == "" {
		what = defaultWhat[f.Kind]
	}
	if what == "" {
		what = "the page template"
	}
	return models.FixCode, "", what
}

// defaultWhat names the template element of a kind fixed in code.
var defaultWhat = map[string]string{
	KindCanonicalMissing: `<link rel="canonical"> in the page head`,
	KindH1Missing:        "the <h1> of the page template",
	KindH1Multiple:       "the <h1> headings of the page template",
	KindHeadingSkipped:   "the heading levels of the page template",
	KindHeadingEmpty:     "the empty heading of the page template",
	KindJSONLDInvalid:    `the <script type="application/ld+json"> of the page template`,
	KindJSONLDMultiple:   `the <script type="application/ld+json"> blocks of the page template`,
	KindHreflangRecip:    `the <link rel="alternate" hreflang> links of the page template`,
	KindImageAlt:         "the alt attribute of the template's <img>",
	KindImageSize:        "the width and height attributes of the template's <img>",
	KindFeaturedLazy:     `loading="lazy" on the main image`,
	KindContentJS:        "server-side rendering of the page content",
	KindGenericAnchor:    "the link text in the page template",
	KindRedirectedLink:   "the link in the page template",
	KindOrphanPage:       "a link to this page from the site navigation or another page",
	KindSitemapNoindex:   "the address list of the sitemap that names this page",
}

// Fingerprint identifies a finding across crawls: the kind, the address,
// the locale and the check (content_js), so an ignore survives later
// crawls (P33-37).
func Fingerprint(kind, url, locale, check string) string {
	sum := sha256.Sum256([]byte(kind + "\x00" + url + "\x00" + locale + "\x00" + check))
	return hex.EncodeToString(sum[:16])
}

// normal is text compared without case and extra whitespace.
func normal(s string) string { return classes.NormalText(s) }