// Models/LocalIssue.swift
// -----------------------
// SwiftData model for issues flagged during an offline inspection.

import Foundation
import SwiftData

@Model
final class LocalIssue {

    @Attribute(.unique) var localId: String
    var serverId: Int?

    var inspectionLocalId: String    // references LocalInspection.localId
    var facilityServerId: Int        // facility this issue belongs to
    /// Server ID of the area this issue was flagged in. Set when flagged during
    /// an inspection that has an area selected. Nil for standalone issues.
    var areaServerId: Int?
    var severity: String             // "low" | "medium" | "high" | "critical"
    var issueDescription: String
    var issueStatus: String = "open"  // server status: "open" | "in_progress" | "resolved" | "pending_verification"
    /// JSON-encoded array of absolute local file paths, e.g. ["/var/.../photo1.jpg", ...]
    var photoLocalPathsJSON: String = "[]"
    /// JSON-encoded array of server paths after upload, e.g. ["uploads/issue_photos/abc.jpg", ...]
    var photoServerPathsJSON: String = "[]"

    // Shared coders — JSONDecoder/Encoder init is expensive (parses locale and
    // calendar info). Allocating them inside computed property getters means
    // a new instance per access; on a list showing 50 issues each with two
    // JSON-backed arrays that's 200 allocations per render pass. Static
    // instances are created once and reused for the lifetime of the app.
    private static let jsonDecoder = JSONDecoder()
    private static let jsonEncoder = JSONEncoder()

    // Lightweight decode cache — avoids re-parsing identical JSON strings.
    // SwiftData may call the getter multiple times per render pass (once for
    // isEmpty, once for count, once for ForEach). Caching the last-decoded
    // value by JSON string identity means the JSON parse only happens when
    // the underlying data actually changes.
    // @Transient tells SwiftData not to persist these — they're in-memory only.
    // Lightweight decode cache — split into key+value pairs because SwiftData's
    // @Transient macro does not support tuple types. Two separate @Transient
    // properties per cache entry achieve the same result with no schema impact.
    @Transient private var _cachedLocalKey:    String   = ""
    @Transient private var _cachedLocalValue:  [String] = []
    @Transient private var _cachedServerKey:   String   = ""
    @Transient private var _cachedServerValue: [String] = []

    /// Decoded local photo paths (up to 5)
    var photoLocalPaths: [String] {
        get {
            if _cachedLocalKey == photoLocalPathsJSON, !_cachedLocalKey.isEmpty {
                return _cachedLocalValue
            }
            let decoded = (try? Self.jsonDecoder.decode([String].self,
                           from: Data(photoLocalPathsJSON.utf8))) ?? []
            _cachedLocalKey   = photoLocalPathsJSON
            _cachedLocalValue = decoded
            return decoded
        }
        set {
            let encoded = (try? String(data: Self.jsonEncoder.encode(newValue),
                                       encoding: .utf8)) ?? "[]"
            photoLocalPathsJSON = encoded
            _cachedLocalKey     = encoded
            _cachedLocalValue   = newValue
        }
    }

    /// Decoded server photo paths
    var photoServerPaths: [String] {
        get {
            if _cachedServerKey == photoServerPathsJSON, !_cachedServerKey.isEmpty {
                return _cachedServerValue
            }
            let decoded = (try? Self.jsonDecoder.decode([String].self,
                           from: Data(photoServerPathsJSON.utf8))) ?? []
            _cachedServerKey   = photoServerPathsJSON
            _cachedServerValue = decoded
            return decoded
        }
        set {
            let encoded = (try? String(data: Self.jsonEncoder.encode(newValue),
                                       encoding: .utf8)) ?? "[]"
            photoServerPathsJSON = encoded
            _cachedServerKey     = encoded
            _cachedServerValue   = newValue
        }
    }

    var createdAt: Date
    var syncStatus: String           // "pending" | "synced" | "failed"
    var syncRetryCount: Int
    var syncErrorMessage: String?

    // ── Phase A additions — persisted from server response ────────────────
    // All new String?/Date? fields default to nil; SwiftData lightweight migration
    // supports nil-default optional properties without a migration plan.

    /// Facility display name cached from the server response. Used when the
    /// local facility reference cache has been cleared (Settings → Clear Cache).
    var facilityNameCache: String?

    /// Server-side reported_at timestamp. More accurate than createdAt for
    /// server-pulled issues because createdAt falls back to device time when
    /// the issue was created offline.
    var serverReportedAt: Date?

    /// Resolution notes added by web staff after fixing the issue.
    var resultNotes: String?

    /// Timestamp when a director/admin verified the fix.
    var verifiedAt: Date?

    /// Note left by the verifier.
    var verificationNote: String?

    /// Display name of the user who originally reported this issue.
    var reportedByName: String?

    /// Name of the area this issue was flagged in (e.g. "Main Lobby").
    /// Set from server response; nil for standalone issues without area context.
    var areaNameCache: String?

    /// Display name of the user currently assigned to this issue.
    /// Nil when unassigned. Updated on every pullAssignedIssues().
    var assignedToName: String?

    // Explicit inverse declared so SwiftData has an unambiguous relationship
    // graph at schema-build time.  Without it the relationship is implicit,
    // which can cause migration warnings or incorrect cascade behaviour on some
    // SwiftData versions.  The deleteRule is .nullify (default) — deleting the
    // parent inspection cascades via LocalInspection.localIssues; this side
    // only nullifies the back-pointer.
    @Relationship(deleteRule: .nullify, inverse: \LocalInspection.localIssues)
    var inspection: LocalInspection?

    init(
        inspectionLocalId: String,
        facilityServerId: Int,
        severity: String,
        description: String
    ) {
        self.localId           = UUID().uuidString
        self.serverId          = nil
        self.inspectionLocalId = inspectionLocalId
        self.facilityServerId  = facilityServerId
        self.areaServerId      = nil
        self.severity          = severity
        self.issueDescription  = description
        self.issueStatus       = "open"
        self.photoLocalPathsJSON  = "[]"
        self.photoServerPathsJSON = "[]"
        self.createdAt         = Date()
        self.syncStatus        = "pending"
        self.syncRetryCount    = 0
        self.syncErrorMessage  = nil
        // Phase A fields — nil by default
        self.facilityNameCache  = nil
        self.serverReportedAt   = nil
        self.resultNotes        = nil
        self.verifiedAt         = nil
        self.verificationNote   = nil
        self.reportedByName     = nil
        self.areaNameCache      = nil
        self.assignedToName     = nil
    }

    var severityColor: String {
        switch severity {
        case "critical": return "red"
        case "high":     return "orange"
        case "medium":   return "yellow"
        default:         return "blue"
        }
    }
}