// Package redfishtree reconstructs a Redfish service-tree snapshot from an
// archive member and turns it into the path->document map expected by
// collector.ReplayRedfishFromRawPayloads.
//
// Some BMC support-bundle tools (seen first on Dell iDRAC10-generation TSR
// exports) capture inventory as a raw crawl of their own Redfish API instead
// of a vendor-specific summary format: one JSON document per resource,
// stored as "<url-path>/index.json" inside a tar.gz or zip, mirroring the
// Redfish URL tree (e.g. "redfish/v1/Systems/System.Embedded.1/index.json").
//
// Detecting one of these dumps is a two-step rule, both vendor-independent:
//  1. Path hint: an archive member whose path contains "redfish" and ends in
//     .tar.gz, .tgz or .zip (e.g. "redfishidracwalk.tar.gz").
//  2. Structural confirmation: once unpacked, the member must contain a JSON
//     document whose own "@odata.id" is exactly "/redfish/v1" (the DMTF
//     Redfish service root), plus at least one of "/redfish/v1/Systems" or
//     "/redfish/v1/Chassis" as a resource collection. Directory-name hints
//     alone are not enough to commit to treating the archive as a Redfish
//     walk; this content check is what confirms it.
//
// Any vendor parser can call FindCandidateArchives + Build to pick up this
// kind of source as enrichment. vendors/redfishwalk registers a low-priority
// fallback VendorParser using the same helpers, for archives that carry a
// walk like this but aren't otherwise claimed by a dedicated vendor parser.
package redfishtree

import (
	"archive/tar"
	"archive/zip"
	"bytes"
	"compress/gzip"
	"encoding/json"
	"io"
	"strings"

	"git.mchus.pro/mchus/logpile/internal/parser"
)

const (
	maxEntryBytes = 8 * 1024 * 1024
	maxTotalBytes = 128 * 1024 * 1024
	maxEntries    = 50000
)

// FindCandidateArchives returns archive members (recursing one level into any
// nested zip, mirroring how vendor support bundles commonly nest archives)
// whose path hints at a captured Redfish walk.
func FindCandidateArchives(files []parser.ExtractedFile) []parser.ExtractedFile {
	var out []parser.ExtractedFile
	consider := func(f parser.ExtractedFile) {
		path := strings.ToLower(strings.TrimSpace(f.Path))
		if !strings.Contains(path, "redfish") {
			return
		}
		if strings.HasSuffix(path, ".tar.gz") || strings.HasSuffix(path, ".tgz") || strings.HasSuffix(path, ".zip") {
			out = append(out, f)
		}
	}

	for _, f := range files {
		consider(f)

		path := strings.ToLower(strings.TrimSpace(f.Path))
		if !strings.HasSuffix(path, ".zip") {
			continue
		}
		zr, err := zip.NewReader(bytes.NewReader(f.Content), int64(len(f.Content)))
		if err != nil {
			continue
		}
		for _, zf := range zr.File {
			if zf.FileInfo().IsDir() || zf.FileInfo().Size() > maxEntryBytes {
				continue
			}
			rc, err := zf.Open()
			if err != nil {
				continue
			}
			content, err := io.ReadAll(rc)
			rc.Close()
			if err != nil {
				continue
			}
			consider(parser.ExtractedFile{Path: zf.Name, Content: content, ModTime: zf.Modified})
		}
	}
	return out
}

// Build reconstructs a path->document tree from a candidate archive member,
// trying tar.gz then zip, and returns nil unless the result passes
// LooksLikeWalk.
func Build(content []byte) map[string]interface{} {
	if tree := BuildFromTarGz(content); LooksLikeWalk(tree) {
		return tree
	}
	if tree := BuildFromZip(content); LooksLikeWalk(tree) {
		return tree
	}
	return nil
}

// BuildFromTarGz unpacks a tar.gz snapshot of a Redfish directory walk into a
// path->document map suitable for collector.ReplayRedfishFromRawPayloads.
func BuildFromTarGz(content []byte) map[string]interface{} {
	gzr, err := gzip.NewReader(bytes.NewReader(content))
	if err != nil {
		return nil
	}
	defer gzr.Close()

	tree := make(map[string]interface{})
	tr := tar.NewReader(gzr)
	totalBytes := 0
	entries := 0
	for {
		hdr, err := tr.Next()
		if err == io.EOF {
			break
		}
		if err != nil {
			break
		}
		if hdr.Typeflag != tar.TypeReg || !strings.HasSuffix(strings.ToLower(hdr.Name), ".json") {
			continue
		}
		entries++
		if entries > maxEntries {
			break
		}
		if hdr.Size <= 0 || hdr.Size > maxEntryBytes {
			continue
		}
		totalBytes += int(hdr.Size)
		if totalBytes > maxTotalBytes {
			break
		}
		raw := make([]byte, hdr.Size)
		if _, err := io.ReadFull(tr, raw); err != nil {
			continue
		}
		addDoc(tree, hdr.Name, raw)
	}
	if len(tree) == 0 {
		return nil
	}
	return tree
}

// BuildFromZip does the same as BuildFromTarGz for a zip-packaged walk.
func BuildFromZip(content []byte) map[string]interface{} {
	zr, err := zip.NewReader(bytes.NewReader(content), int64(len(content)))
	if err != nil {
		return nil
	}

	tree := make(map[string]interface{})
	totalBytes := 0
	entries := 0
	for _, zf := range zr.File {
		if zf.FileInfo().IsDir() || !strings.HasSuffix(strings.ToLower(zf.Name), ".json") {
			continue
		}
		entries++
		if entries > maxEntries {
			break
		}
		size := zf.FileInfo().Size()
		if size <= 0 || size > maxEntryBytes {
			continue
		}
		totalBytes += int(size)
		if totalBytes > maxTotalBytes {
			break
		}
		rc, err := zf.Open()
		if err != nil {
			continue
		}
		raw, err := io.ReadAll(rc)
		rc.Close()
		if err != nil {
			continue
		}
		addDoc(tree, zf.Name, raw)
	}
	if len(tree) == 0 {
		return nil
	}
	return tree
}

func addDoc(tree map[string]interface{}, entryName string, raw []byte) {
	var doc map[string]interface{}
	if err := json.Unmarshal(raw, &doc); err != nil {
		return
	}
	key := treeKey(entryName, doc)
	if key == "" {
		return
	}
	tree[key] = doc
}

// treeKey prefers the document's own @odata.id (always unencoded) over the
// archive's on-disk path, since some resource names (e.g. "Assembly#") are
// URL-encoded as directory names but not in the JSON payload itself.
func treeKey(entryName string, doc map[string]interface{}) string {
	if id, ok := doc["@odata.id"].(string); ok {
		if p := normalizePath(id); p != "" {
			return p
		}
	}
	name := strings.TrimSuffix(entryName, "index.json")
	name = strings.TrimSuffix(name, ".json")
	return normalizePath(name)
}

func normalizePath(p string) string {
	p = strings.TrimSpace(p)
	if p == "" {
		return ""
	}
	if !strings.HasPrefix(p, "/") {
		p = "/" + p
	}
	if len(p) > 1 {
		p = strings.TrimSuffix(p, "/")
	}
	return p
}

// LooksLikeWalk reports whether tree has the minimum structural shape of a
// real Redfish service tree: a /redfish/v1 service root plus at least one of
// a Systems or Chassis collection. This is the stable, vendor-independent
// signature used to confirm a candidate archive before committing to it.
func LooksLikeWalk(tree map[string]interface{}) bool {
	if tree == nil {
		return false
	}
	if _, ok := tree["/redfish/v1"]; !ok {
		return false
	}
	_, hasSystems := tree["/redfish/v1/Systems"]
	_, hasChassis := tree["/redfish/v1/Chassis"]
	return hasSystems || hasChassis
}