// ingestion/internal/pipeline/resolve.go
package pipeline

import (
	"path/filepath"
	"strings"

	"github.com/mathiasbq/hyperguild/ingestion/internal/wiki"
)

// Resolve remaps proposed pages to existing slugs when a fuzzy title match is found.
// It only matches within the same page type (entities→entities, concepts→concepts).
// Pages with no inventory match are returned unchanged.
func Resolve(proposed []wiki.Page, inventory map[wiki.PageType][]wiki.Entry) []wiki.Page {
	type key struct {
		pt         wiki.PageType
		normalized string
	}
	lookup := make(map[key]string) // key → canonical slug
	for pt, entries := range inventory {
		for _, e := range entries {
			k := key{pt: pt, normalized: normalizeTitle(e.Title)}
			lookup[k] = e.Slug
			for _, alias := range e.Aliases {
				ak := key{pt: pt, normalized: normalizeTitle(alias)}
				if _, exists := lookup[ak]; !exists {
					lookup[ak] = e.Slug
				}
			}
		}
	}

	out := make([]wiki.Page, 0, len(proposed))
	for _, page := range proposed {
		pt := pageTypeFromPath(page.Path)
		title := extractTitle(page.Content)
		k := key{pt: pt, normalized: normalizeTitle(title)}
		if canonicalSlug, ok := lookup[k]; ok {
			dir := filepath.Dir(page.Path)
			page.Path = dir + "/" + canonicalSlug + ".md"
		}
		out = append(out, page)
	}
	return out
}

// normalizeTitle lowercases, removes leading articles, collapses whitespace.
// "The Shape Up Method" → "shape up method"
func normalizeTitle(s string) string {
	s = strings.ToLower(strings.TrimSpace(s))
	for _, article := range []string{"the ", "a ", "an "} {
		s = strings.TrimPrefix(s, article)
	}
	s = strings.ReplaceAll(s, "-", " ")
	return strings.Join(strings.Fields(s), " ")
}

// pageTypeFromPath extracts the wiki.PageType from a path like "wiki/entities/foo.md".
func pageTypeFromPath(path string) wiki.PageType {
	parts := strings.Split(filepath.ToSlash(path), "/")
	if len(parts) >= 2 {
		return wiki.PageType(parts[1])
	}
	return ""
}

// extractTitle reads the title field from YAML frontmatter in content.
// Falls back to empty string if not found.
func extractTitle(content string) string {
	lines := strings.SplitN(content, "\n", 30)
	inFM := false
	for _, line := range lines {
		if strings.TrimSpace(line) == "---" {
			if !inFM {
				inFM = true
				continue
			}
			break
		}
		if inFM {
			key, val, ok := strings.Cut(line, ":")
			if ok && strings.TrimSpace(key) == "title" {
				return strings.Trim(strings.TrimSpace(val), `"'`)
			}
		}
	}
	return ""
}