package main

import (
	"context"
	"fmt"
	"strings"
	"time"
)

func runDiscussion(ctx context.Context, cache *Cache, loc Location, searchQuery, userAgent string) (string, error) {
	client := NewNWSClient(userAgent)
	if loc.OfficeID == "" {
		office, err := client.FetchOfficeID(ctx, loc)
		if err != nil {
			return "", err
		}
		loc.OfficeID = office
		if err := cache.UpdateLocation(loc); err != nil {
			if searchQuery == "" {
				return "", err
			}
			if err := cache.SaveLocation(searchQuery, loc); err != nil {
				return "", err
			}
		}
	}

	cached, ok, err := cache.LoadAFD()
	if err != nil {
		return "", err
	}

	productID, productURL, err := client.FetchLatestAFDMeta(ctx, loc.OfficeID)
	if err != nil {
		return "", err
	}

	if ok && cached.OfficeID == loc.OfficeID && cached.ProductID == productID {
		cached.CheckedAt = time.Now().UTC()
		if err := cache.SaveAFD(cached); err != nil {
			return "", err
		}
		return cached.Text, nil
	}

	text, issuanceTime, err := client.FetchAFDText(ctx, productURL)
	if err != nil {
		return "", err
	}

	payload := AFDCache{
		OfficeID:     loc.OfficeID,
		ProductID:    productID,
		Text:         text,
		IssuanceTime: issuanceTime,
		CheckedAt:    time.Now().UTC(),
	}
	if err := cache.SaveAFD(payload); err != nil {
		return "", err
	}
	return text, nil
}

func (c *NWSClient) FetchLatestAFDMeta(ctx context.Context, officeID string) (string, string, error) {
	officeID = strings.TrimSpace(strings.ToUpper(officeID))
	if officeID == "" {
		return "", "", fmt.Errorf("office id is empty")
	}

	url := fmt.Sprintf("https://api.weather.gov/products/types/AFD/locations/%s", officeID)
	var resp struct {
		Graph []struct {
			ID  string `json:"id"`
			Ref string `json:"@id"`
		} `json:"@graph"`
	}
	if err := c.getJSON(ctx, url, &resp); err != nil {
		return "", "", err
	}
	if len(resp.Graph) == 0 {
		return "", "", fmt.Errorf("no AFD products for %s", officeID)
	}
	productID := strings.TrimSpace(resp.Graph[0].ID)
	productURL := strings.TrimSpace(resp.Graph[0].Ref)
	if productID == "" || productURL == "" {
		return "", "", fmt.Errorf("invalid AFD metadata")
	}
	return productID, productURL, nil
}

func (c *NWSClient) FetchAFDText(ctx context.Context, url string) (string, string, error) {
	var resp struct {
		ProductText  string `json:"productText"`
		IssuanceTime string `json:"issuanceTime"`
	}
	if err := c.getJSON(ctx, url, &resp); err != nil {
		return "", "", err
	}
	text := sanitizeAFDText(resp.ProductText)
	if text == "" {
		return "", "", fmt.Errorf("AFD product text missing")
	}
	return text, strings.TrimSpace(resp.IssuanceTime), nil
}

func sanitizeAFDText(text string) string {
	lines := strings.Split(strings.ReplaceAll(text, "\r\n", "\n"), "\n")
	for len(lines) > 0 && strings.TrimSpace(lines[0]) == "" {
		lines = lines[1:]
	}
	if len(lines) == 0 {
		return ""
	}

	for i, line := range lines {
		if strings.Contains(strings.ToLower(line), "area forecast discussion") {
			lines = lines[i:]
			break
		}
	}

	for len(lines) > 0 && strings.TrimSpace(lines[0]) == "" {
		lines = lines[1:]
	}
	return strings.TrimSpace(strings.Join(lines, "\n"))
}

func formatAFDMarkdown(text string) string {
	lines := strings.Split(strings.ReplaceAll(text, "\r\n", "\n"), "\n")
	out := make([]string, 0, len(lines))
	titleDone := false
	for _, line := range lines {
		trimmed := strings.TrimSpace(line)
		if trimmed == "&&" {
			continue
		}
		if !titleDone && strings.EqualFold(trimmed, "Area Forecast Discussion") {
			out = append(out, "# Area Forecast Discussion")
			titleDone = true
			continue
		}
		if header, rest := splitKeyMessage(trimmed); header != "" {
			out = append(out, "## "+header)
			if rest != "" {
				out = append(out, rest)
			}
			continue
		}
		if isAFDHeaderLine(trimmed) {
			title := afdHeaderToTitle(trimmed)
			out = append(out, "# "+title)
			continue
		}
		out = append(out, line)
	}
	return strings.TrimSpace(strings.Join(out, "\n"))
}

func isAFDHeaderLine(line string) bool {
	if !strings.HasPrefix(line, ".") {
		return false
	}
	return strings.HasSuffix(line, "...") || strings.HasSuffix(line, ".")
}

func afdHeaderToTitle(line string) string {
	trimmed := strings.Trim(line, ". ")
	parts := strings.Fields(trimmed)
	for i, part := range parts {
		subparts := strings.Split(part, "/")
		for j, sub := range subparts {
			subparts[j] = titleWord(sub)
		}
		parts[i] = strings.Join(subparts, "/")
	}
	return strings.Join(parts, " ")
}

func titleWord(word string) string {
	if word == "" {
		return ""
	}
	lower := strings.ToLower(word)
	r := []rune(lower)
	r[0] = []rune(strings.ToUpper(string(r[0])))[0]
	return string(r)
}

func splitKeyMessage(line string) (string, string) {
	lower := strings.ToLower(line)
	if !strings.HasPrefix(lower, "key message") {
		return "", ""
	}
	parts := strings.SplitN(line, "...", 2)
	header := strings.TrimSpace(parts[0])
	rest := ""
	if len(parts) > 1 {
		rest = strings.TrimSpace(parts[1])
	}
	fields := strings.Fields(header)
	if len(fields) < 2 {
		return "", ""
	}
	fields[0] = "Key"
	fields[1] = "Message"
	return strings.Join(fields, " "), rest
}