package radarfetch

import (
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
)

type Bounds struct {
	West  float64 `json:"west"`
	South float64 `json:"south"`
	East  float64 `json:"east"`
	North float64 `json:"north"`
}

type Sources struct {
	NmcHTML string `json:"nmc_html"`
	NmcImg  string `json:"nmc_img"`
	CmaBin  string `json:"cma_bin"`
}

type Files struct {
	HTML     string `json:"html"`
	PNG      string `json:"png"`
	BIN      string `json:"bin"`
	Metadata string `json:"metadata"`
	CMAPNG   string `json:"cma_png"`
}

type Sizes struct {
	PNG int64 `json:"png"`
	BIN int64 `json:"bin"`
}

type Metadata struct {
	TimestampLocal string  `json:"timestamp_local"`
	Date           int     `json:"date"`
	Hour           int     `json:"hour"`
	Minute         int     `json:"minute"`
	Z              int     `json:"z"`
	Y              int     `json:"y"`
	X              int     `json:"x"`
	Bounds         Bounds  `json:"bounds"`
	ResDeg         float64 `json:"res_deg"`
	Sources        Sources `json:"sources"`
	Files          Files   `json:"files"`
	Sizes          Sizes   `json:"sizes"`
	CreatedAt      string  `json:"created_at"`
	// Cloud clusters detected from single-frame CREF (>=40 dBZ)
	// Optional; may be empty when detection fails.
	Clusters []Cluster `json:"clusters,omitempty"`
	// Optional notes about sampling strategy or thresholds used
	AnalysisNote string `json:"analysis_note,omitempty"`
	// Wind query planning parameters and candidates
	QueryParams     QueryParams      `json:"query_params,omitempty"`
	QueryCandidates []QueryCandidate `json:"query_candidates,omitempty"`
}

// Cluster represents a connected echo region above threshold.
type Cluster struct {
	ID     int     `json:"id"`
	AreaPx int     `json:"area_px"`
	MaxDBZ float64 `json:"max_dbz"`
	AvgDBZ float64 `json:"avg_dbz"`
	// Pixel-space centroid (row, col) using dBZ-weighted center
	Row int `json:"row"`
	Col int `json:"col"`
	// Centroid lon/lat of pixel center
	Lon float64 `json:"lon"`
	Lat float64 `json:"lat"`
	// Bounding box in pixel coords (inclusive)
	MinRow int `json:"min_row"`
	MinCol int `json:"min_col"`
	MaxRow int `json:"max_row"`
	MaxCol int `json:"max_col"`
	// Recommended sample points for downstream wind queries
	Samples []Sample `json:"samples"`
	// Optional path to a small PNG rendering of this cluster (copied to latest)
	PNG string `json:"png,omitempty"`
	// Eligibility for downstream wind query
	EligibleForQuery bool   `json:"eligible_for_query,omitempty"`
	SkipReason       string `json:"skip_reason,omitempty"`
}

type Sample struct {
	Row int     `json:"row"`
	Col int     `json:"col"`
	Lon float64 `json:"lon"`
	Lat float64 `json:"lat"`
	// role: center | ray_n | ray_s | ray_e | ray_w
	Role string `json:"role"`
}

// Parameters controlling wind query candidate selection.
type QueryParams struct {
	MinAreaPx            int     `json:"min_area_px"`
	StrongDBZOverride    float64 `json:"strong_dbz_override"`
	MaxSamplesPerCluster int     `json:"max_samples_per_cluster"`
	MaxCandidatesTotal   int     `json:"max_candidates_total"`
}

// A single candidate point to query external wind API.
type QueryCandidate struct {
	ClusterID int     `json:"cluster_id"`
	Role      string  `json:"role"`
	Lon       float64 `json:"lon"`
	Lat       float64 `json:"lat"`
}

func WriteMetadata(path string, m *Metadata) error {
	b, err := json.MarshalIndent(m, "", "  ")
	if err != nil {
		return err
	}
	return os.WriteFile(path, b, 0o644)
}

func UpdateLatest(root string, curDir string, m *Metadata) error {
	latest := filepath.Join(root, "latest")
	if err := os.MkdirAll(latest, 0o755); err != nil {
		return err
	}
	// Write latest.json
	b, _ := json.MarshalIndent(struct {
		Dir  string    `json:"dir"`
		Meta *Metadata `json:"meta"`
	}{Dir: curDir, Meta: m}, "", "  ")
	_ = os.WriteFile(filepath.Join(latest, "latest.json"), b, 0o644)

	copyFile := func(name string) {
		dst := filepath.Join(latest, name)
		src := filepath.Join(curDir, name)
		data, e2 := os.ReadFile(src)
		if e2 == nil {
			// ensure parent dir exists for nested paths like "clusters/..."
			_ = os.MkdirAll(filepath.Dir(dst), 0o755)
			_ = os.WriteFile(dst, data, 0o644)
		}
	}
	copyFile("nmc_chinaall.png")
	copyFile("nmc_huanan.png")
	copyFile("nmc_nanning.png")
	copyFile("metadata.json")
	copyFile(fmt.Sprintf("%d-%d-%d.bin", m.Z, m.Y, m.X))
	if m.Files.CMAPNG != "" {
		copyFile(filepath.Base(m.Files.CMAPNG))
	}
	// copy cluster PNGs if present
	if len(m.Clusters) > 0 {
		for _, cl := range m.Clusters {
			if cl.PNG == "" {
				continue
			}
			copyFile(cl.PNG)
		}
	}
	return nil
}