import SwiftUI

struct SessionConfigurationPanel: View {
    @State private var session = SessionStore.shared

    let title: String
    let subtitle: String
    let primaryActionTitle: String
    let allowsClearingStoredConfiguration: Bool

    var body: some View {
        @Bindable var session = session

        VStack(alignment: .leading, spacing: 18) {
            VStack(alignment: .leading, spacing: 6) {
                Text(title)
                    .font(.system(size: 18, weight: .semibold))
                    .foregroundStyle(VelocityTheme.foreground)
                Text(subtitle)
                    .font(.system(size: 12))
                    .foregroundStyle(VelocityTheme.mutedFg)
            }

            VStack(spacing: 14) {
                SessionInputField(
                    label: "Backend endpoint",
                    placeholder: "https://velocity.desineuron.in/api"
                ) {
                    TextField("", text: $session.draftBaseURL, prompt: Text("https://velocity.desineuron.in/api"))
                        .textInputAutocapitalization(.never)
                        .autocorrectionDisabled()
                        .keyboardType(.URL)
                }

                SessionInputField(
                    label: "Dream Weaver endpoint",
                    placeholder: "Leave blank to use the backend endpoint"
                ) {
                    TextField("", text: $session.draftDreamWeaverBaseURL, prompt: Text("https://dreamweaver.desineuron.in"))
                        .textInputAutocapitalization(.never)
                        .autocorrectionDisabled()
                        .keyboardType(.URL)
                }

                SessionInputField(
                    label: "Dream Weaver gateway API key",
                    placeholder: session.currentConfiguration.hasDreamWeaverAPIKey ? "Leave blank to keep the current gateway key" : "Optional unless the gateway enforces it"
                ) {
                    SecureField(
                        "",
                        text: $session.draftDreamWeaverAPIKey,
                        prompt: Text(session.currentConfiguration.hasDreamWeaverAPIKey ? "Leave blank to keep the current gateway key" : "Optional unless the gateway enforces it")
                    )
                    .textInputAutocapitalization(.never)
                    .autocorrectionDisabled()
                }

                VStack(alignment: .leading, spacing: 8) {
                    Text("Authentication mode")
                        .font(.system(size: 12, weight: .medium))
                        .foregroundStyle(VelocityTheme.mutedFg)

                    Picker("Authentication mode", selection: $session.draftAuthMode) {
                        ForEach(SessionAuthMode.allCases) { mode in
                            Text(mode.rawValue).tag(mode)
                        }
                    }
                    .pickerStyle(.segmented)
                }

                if session.draftAuthMode == .emailPassword {
                    SessionInputField(
                        label: "Operator email",
                        placeholder: "operator@desineuron.in"
                    ) {
                        TextField("", text: $session.draftEmail, prompt: Text("operator@desineuron.in"))
                            .textInputAutocapitalization(.never)
                            .autocorrectionDisabled()
                            .keyboardType(.emailAddress)
                    }

                    SessionInputField(
                        label: "Password",
                        placeholder: session.currentConfiguration.hasPassword ? "Leave blank to keep the current secret" : "Required"
                    ) {
                        SecureField(
                            "",
                            text: $session.draftPassword,
                            prompt: Text(session.currentConfiguration.hasPassword ? "Leave blank to keep the current secret" : "Required")
                        )
                        .textInputAutocapitalization(.never)
                        .autocorrectionDisabled()
                    }
                } else {
                    SessionInputField(
                        label: "Bearer token",
                        placeholder: session.currentConfiguration.hasBearerToken ? "Leave blank to keep the current token" : "Required"
                    ) {
                        SecureField(
                            "",
                            text: $session.draftBearerToken,
                            prompt: Text(session.currentConfiguration.hasBearerToken ? "Leave blank to keep the current token" : "Required")
                        )
                        .textInputAutocapitalization(.never)
                        .autocorrectionDisabled()
                    }
                }
            }

            VStack(alignment: .leading, spacing: 4) {
                Text("Current source: \(session.configurationSourceDescription)")
                    .font(.system(size: 12, weight: .medium))
                    .foregroundStyle(VelocityTheme.foreground)
                Text("Runtime overrides are saved on-device. Secrets are stored in Keychain; the backend endpoint, optional Dream Weaver endpoint, and operator email are stored in local app preferences.")
                    .font(.system(size: 11))
                    .foregroundStyle(VelocityTheme.mutedFg)
            }

            if let message = session.statusMessage {
                SessionStatusBanner(message: message, accentColor: VelocityTheme.success)
            }

            if let error = session.errorMessage {
                SessionStatusBanner(message: error, accentColor: VelocityTheme.danger)
            }

            HStack(spacing: 12) {
                Button {
                    Task { await session.saveDraft() }
                } label: {
                    HStack(spacing: 8) {
                        if session.isSaving {
                            ProgressView()
                                .progressViewStyle(CircularProgressViewStyle(tint: .white))
                                .tint(.white)
                        }
                        Text(primaryActionTitle)
                            .font(.system(size: 14, weight: .semibold))
                    }
                    .frame(maxWidth: .infinity)
                    .padding(.vertical, 12)
                }
                .buttonStyle(SessionActionButtonStyle(background: VelocityTheme.accent))
                .disabled(session.isSaving)

                Button("Reset form") {
                    session.discardDraftChanges()
                }
                .buttonStyle(SessionSecondaryButtonStyle())
                .disabled(session.isSaving || !session.hasUnsavedChanges)
            }

            if allowsClearingStoredConfiguration {
                Button("Clear stored session override") {
                    Task { await session.clearStoredConfiguration() }
                }
                .buttonStyle(SessionDangerButtonStyle())
                .disabled(session.isSaving || !session.isUsingStoredRuntimeConfiguration)
            }
        }
        .padding(20)
        .glassCard(cornerRadius: 20)
    }
}

private struct SessionInputField<Field: View>: View {
    let label: String
    let placeholder: String
    @ViewBuilder let field: Field

    var body: some View {
        VStack(alignment: .leading, spacing: 8) {
            Text(label)
                .font(.system(size: 12, weight: .medium))
                .foregroundStyle(VelocityTheme.mutedFg)

            field
                .font(.system(size: 14))
                .foregroundStyle(VelocityTheme.foreground)
                .padding(.horizontal, 14)
                .padding(.vertical, 12)
                .background(
                    RoundedRectangle(cornerRadius: 12)
                        .fill(VelocityTheme.surface)
                        .overlay(
                            RoundedRectangle(cornerRadius: 12)
                                .stroke(VelocityTheme.borderSubtle, lineWidth: 1)
                        )
                )

            Text(placeholder)
                .font(.system(size: 10))
                .foregroundStyle(VelocityTheme.mutedFg.opacity(0.9))
        }
    }
}

private struct SessionStatusBanner: View {
    let message: String
    let accentColor: Color

    var body: some View {
        Text(message)
            .font(.system(size: 12, weight: .medium))
            .foregroundStyle(accentColor)
            .padding(.horizontal, 14)
            .padding(.vertical, 12)
            .frame(maxWidth: .infinity, alignment: .leading)
            .background(
                RoundedRectangle(cornerRadius: 12)
                    .fill(accentColor.opacity(0.10))
                    .overlay(
                        RoundedRectangle(cornerRadius: 12)
                            .stroke(accentColor.opacity(0.18), lineWidth: 1)
                    )
            )
    }
}

private struct SessionActionButtonStyle: ButtonStyle {
    let background: Color

    func makeBody(configuration: Configuration) -> some View {
        configuration.label
            .foregroundStyle(.white)
            .background(
                RoundedRectangle(cornerRadius: 12)
                    .fill(background.opacity(configuration.isPressed ? 0.82 : 1))
            )
    }
}

private struct SessionSecondaryButtonStyle: ButtonStyle {
    func makeBody(configuration: Configuration) -> some View {
        configuration.label
            .font(.system(size: 14, weight: .medium))
            .foregroundStyle(VelocityTheme.foreground)
            .padding(.horizontal, 18)
            .padding(.vertical, 12)
            .background(
                RoundedRectangle(cornerRadius: 12)
                    .fill(VelocityTheme.surface.opacity(configuration.isPressed ? 0.78 : 1))
                    .overlay(
                        RoundedRectangle(cornerRadius: 12)
                            .stroke(VelocityTheme.borderSubtle, lineWidth: 1)
                    )
            )
    }
}

private struct SessionDangerButtonStyle: ButtonStyle {
    func makeBody(configuration: Configuration) -> some View {
        configuration.label
            .font(.system(size: 13, weight: .medium))
            .foregroundStyle(VelocityTheme.danger)
            .padding(.horizontal, 14)
            .padding(.vertical, 11)
            .background(
                RoundedRectangle(cornerRadius: 12)
                    .fill(VelocityTheme.danger.opacity(configuration.isPressed ? 0.14 : 0.10))
                    .overlay(
                        RoundedRectangle(cornerRadius: 12)
                            .stroke(VelocityTheme.danger.opacity(0.2), lineWidth: 1)
                    )
            )
    }
}