//go:build llm_script

package main

import (
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
	"regexp"
	"sort"
	"strings"
	"time"
)

type vertexPricingStructureSignature struct {
	ByteSize            int            `json:"byte_size"`
	SHA256              string         `json:"sha256"`
	StructureSHA256     string         `json:"structure_sha256"`
	NormalizedLineCount int            `json:"normalized_line_count"`
	TagCounts           map[string]int `json:"tag_counts"`
	Headings            []string       `json:"headings"`
	ContainsGemini      bool           `json:"contains_gemini"`
	ContainsStandard    bool           `json:"contains_standard"`
	ContainsPriceText   bool           `json:"contains_price_text"`
	ContainsTable       bool           `json:"contains_table"`
	GeneratedAt         string         `json:"generated_at,omitempty"`
	SourceURL           string         `json:"source_url,omitempty"`
	SnapshotPath        string         `json:"snapshot_path,omitempty"`
}

var vertexSignatureTagPattern = regexp.MustCompile(`(?is)<(html|body|section|div|table|tr|td|th|h1|h2|h3|h4|h5|h6|script|article)\b`)

func buildVertexPricingStructureSignature(raw string) vertexPricingStructureSignature {
	lines := htmlLines(raw)
	tagCounts := make(map[string]int)
	matches := vertexSignatureTagPattern.FindAllStringSubmatch(raw, -1)
	for _, match := range matches {
		tagCounts[strings.ToLower(match[1])]++
	}

	headings := extractVertexSignatureHeadings(raw)
	signature := vertexPricingStructureSignature{
		ByteSize:            len([]byte(raw)),
		SHA256:              sha256Hex(raw),
		NormalizedLineCount: len(lines),
		TagCounts:           tagCounts,
		Headings:            headings,
		ContainsGemini:      strings.Contains(strings.ToLower(raw), "gemini"),
		ContainsStandard:    containsLine(lines, "standard"),
		ContainsPriceText:   strings.Contains(strings.ToLower(raw), "price"),
		ContainsTable:       tagCounts["table"] > 0,
	}
	signature.StructureSHA256 = sha256Hex(vertexStructureDigestPayload(signature))
	return signature
}

func writeVertexPricingSnapshotArtifacts(raw string, sourceURL string, snapshotPath string, signaturePath string, now time.Time) (vertexPricingStructureSignature, error) {
	if strings.TrimSpace(snapshotPath) == "" {
		return vertexPricingStructureSignature{}, fmt.Errorf("snapshot path is required")
	}
	if strings.TrimSpace(signaturePath) == "" {
		return vertexPricingStructureSignature{}, fmt.Errorf("signature path is required")
	}
	if err := os.MkdirAll(filepath.Dir(snapshotPath), 0o755); err != nil {
		return vertexPricingStructureSignature{}, fmt.Errorf("mkdir snapshot dir: %w", err)
	}
	if err := os.MkdirAll(filepath.Dir(signaturePath), 0o755); err != nil {
		return vertexPricingStructureSignature{}, fmt.Errorf("mkdir signature dir: %w", err)
	}
	if err := os.WriteFile(snapshotPath, []byte(raw), 0o644); err != nil {
		return vertexPricingStructureSignature{}, fmt.Errorf("write snapshot: %w", err)
	}

	signature := buildVertexPricingStructureSignature(raw)
	signature.GeneratedAt = now.Format(time.RFC3339)
	signature.SourceURL = sourceURL
	signature.SnapshotPath = snapshotPath
	payload, err := json.MarshalIndent(signature, "", "  ")
	if err != nil {
		return vertexPricingStructureSignature{}, fmt.Errorf("marshal signature: %w", err)
	}
	if err := os.WriteFile(signaturePath, payload, 0o644); err != nil {
		return vertexPricingStructureSignature{}, fmt.Errorf("write signature: %w", err)
	}
	return signature, nil
}

func resolveVertexPricingSnapshotPaths(snapshotPath string, signaturePath string, now time.Time) (string, string) {
	if strings.TrimSpace(snapshotPath) == "" {
		base := filepath.Join("logs", "vertex-pricing-snapshots", fmt.Sprintf("vertex-pricing-%s", now.Format("20060102-150405")))
		snapshotPath = base + ".html"
		if strings.TrimSpace(signaturePath) == "" {
			signaturePath = base + ".signature.json"
		}
	}
	if strings.TrimSpace(signaturePath) == "" {
		signaturePath = strings.TrimSuffix(snapshotPath, filepath.Ext(snapshotPath)) + ".signature.json"
	}
	return snapshotPath, signaturePath
}

func extractVertexSignatureHeadings(raw string) []string {
	matches := vertexHeadingPattern.FindAllStringSubmatchIndex(raw, -1)
	headings := make([]string, 0, len(matches))
	seen := make(map[string]struct{})
	for _, match := range matches {
		heading := cleanHTMLText(raw[match[2]:match[3]])
		if heading == "" {
			continue
		}
		if _, exists := seen[heading]; exists {
			continue
		}
		seen[heading] = struct{}{}
		headings = append(headings, heading)
		if len(headings) >= 12 {
			break
		}
	}
	return headings
}

func vertexStructureDigestPayload(signature vertexPricingStructureSignature) string {
	type tagCount struct {
		Name  string `json:"name"`
		Count int    `json:"count"`
	}
	tagNames := make([]string, 0, len(signature.TagCounts))
	for name := range signature.TagCounts {
		tagNames = append(tagNames, name)
	}
	sort.Strings(tagNames)
	tagCounts := make([]tagCount, 0, len(tagNames))
	for _, name := range tagNames {
		tagCounts = append(tagCounts, tagCount{Name: name, Count: signature.TagCounts[name]})
	}
	payload := struct {
		NormalizedLineCount int        `json:"normalized_line_count"`
		TagCounts           []tagCount `json:"tag_counts"`
		Headings            []string   `json:"headings"`
		ContainsGemini      bool       `json:"contains_gemini"`
		ContainsStandard    bool       `json:"contains_standard"`
		ContainsPriceText   bool       `json:"contains_price_text"`
		ContainsTable       bool       `json:"contains_table"`
	}{
		NormalizedLineCount: signature.NormalizedLineCount,
		TagCounts:           tagCounts,
		Headings:            signature.Headings,
		ContainsGemini:      signature.ContainsGemini,
		ContainsStandard:    signature.ContainsStandard,
		ContainsPriceText:   signature.ContainsPriceText,
		ContainsTable:       signature.ContainsTable,
	}
	bytes, _ := json.Marshal(payload)
	return string(bytes)
}

func sha256Hex(raw string) string {
	sum := sha256.Sum256([]byte(raw))
	return hex.EncodeToString(sum[:])
}

func containsLine(lines []string, target string) bool {
	for _, line := range lines {
		if strings.EqualFold(strings.TrimSpace(line), target) {
			return true
		}
	}
	return false
}