import { useCallback, useEffect, useMemo, useRef, useState } from "react";
import { bootstrapRuntime, getRuntimeSnapshot, saveRuntimeConfig, scanRuntimeModels, startRuntime, stopRuntime } from "./api";
import {
  createDefaultRuntimeSnapshot,
  createRuntimeLifecycleResult,
  getRuntimeApplyImpact,
  getRuntimeConnection,
  getRuntimeHealthSummary,
  getRuntimeWorkspaceSummary,
  validateModelFile,
  validateModelsDirectory,
  validateSourceMode,
} from "./runtime-utils";
import { createRuntimeDraftFieldState, createRuntimeDraftState } from "./types";
import type {
  RuntimeApplyImpact,
  RuntimeConfig,
  RuntimeDraftFieldKey,
  RuntimeDraftFieldMeta,
  RuntimeDraftState,
  RuntimeLifecycleCommand,
  RuntimeLifecycleResult,
  RuntimeModelFile,
  RuntimeSnapshot,
  RuntimeWorkspaceHealth,
  RuntimeWorkspaceSummary,
} from "./types";

function areConfigsEqual(left: RuntimeConfig, right: RuntimeConfig): boolean {
  return JSON.stringify(left) === JSON.stringify(right);
}

function cloneConfig(config: RuntimeConfig): RuntimeConfig {
  return {
    ...config,
    extra_model_paths: [...config.extra_model_paths],
    remote_presets: config.remote_presets.map((preset) => ({ ...preset })),
  };
}

function applyOperationalSnapshot(current: RuntimeSnapshot, next: RuntimeSnapshot): RuntimeSnapshot {
  return {
    ...current,
    status: next.status,
    ready: next.ready,
    process_running: next.process_running,
    resolved_url: next.resolved_url,
    binary_path: next.binary_path,
    last_error: next.last_error,
    active_command: next.active_command,
    last_command_result: next.last_command_result,
  };
}

function normalizeSnapshot(snapshot: RuntimeSnapshot): RuntimeSnapshot {
  return {
    ...createDefaultRuntimeSnapshot(),
    ...snapshot,
    config: {
      ...createDefaultRuntimeSnapshot().config,
      ...snapshot.config,
    },
    last_command_result:
      snapshot.last_command_result ?? createRuntimeLifecycleResult(snapshot.active_command ?? "idle"),
    active_command: snapshot.active_command ?? "idle",
  };
}

function reconcileDraftState(current: RuntimeDraftState, next: RuntimeSnapshot): RuntimeDraftState {
  const normalizedNext = normalizeSnapshot(next);

  if (current.isDirty) {
    return {
      ...current,
      liveSnapshot: applyOperationalSnapshot(current.liveSnapshot, normalizedNext),
    };
  }

  // Run source-mode validation when reconciling to baseline
  const validation = validateSourceMode(normalizedNext.config);
  const updatedFields = createRuntimeDraftFieldState();
  for (const [fieldName, fieldValidation] of Object.entries(validation.fieldValidations)) {
    updatedFields[fieldName as RuntimeDraftFieldKey] = {
      invalid: !fieldValidation.valid,
      pending: false,
      message: fieldValidation.message,
    };
  }

  return {
    ...current,
    liveSnapshot: normalizedNext,
    savedBaseline: cloneConfig(normalizedNext.config),
    draftConfig: cloneConfig(normalizedNext.config),
    fields: updatedFields,
    // Preserve scanned models state during reconciliation
    scannedModels: current.scannedModels,
    isScanning: current.isScanning,
  };
}

function blockWhileLifecycleBusy(
  snapshot: RuntimeSnapshot,
  command: RuntimeLifecycleCommand,
): RuntimeSnapshot | null {
  if (snapshot.active_command === "idle") {
    return null;
  }

  const blockedBy = snapshot.active_command;
  const message =
    blockedBy === "start"
      ? "Local API start already in progress."
      : blockedBy === "stop"
        ? "Local API stop already in progress."
        : blockedBy === "save"
          ? "Runtime settings save already in progress."
          : "Runtime save and start already in progress.";

  return {
    ...snapshot,
    last_command_result: createRuntimeLifecycleResult(command, message, "blocked"),
  };
}

function startLifecycleSnapshot(
  snapshot: RuntimeSnapshot,
  command: RuntimeLifecycleCommand,
  status: RuntimeSnapshot["status"],
): RuntimeSnapshot {
  return {
    ...snapshot,
    status,
    process_running: command === "start" ? true : snapshot.process_running,
    ready: false,
    last_error: null,
    active_command: command,
  };
}

function finalizeLifecycleSnapshot(
  fallbackCommand: RuntimeLifecycleCommand,
  fallbackMessage: string,
  next: RuntimeSnapshot,
): RuntimeSnapshot {
  const normalizedNext = normalizeSnapshot(next);
  if (normalizedNext.last_command_result.command !== "idle") {
    return normalizedNext;
  }

  return {
    ...normalizedNext,
    last_command_result: createRuntimeLifecycleResult(fallbackCommand, fallbackMessage),
  };
}

export function useRuntimeManager() {
  const [draftState, setDraftState] = useState<RuntimeDraftState>(() =>
    createRuntimeDraftState(createDefaultRuntimeSnapshot()),
  );
  const [loading, setLoading] = useState(true);
  const [busy, setBusy] = useState(false);

  const refresh = useCallback(async () => {
    const next = await getRuntimeSnapshot();
    setDraftState((current) => reconcileDraftState(current, next));
    return next;
  }, []);

  useEffect(() => {
    let active = true;

    bootstrapRuntime()
      .then((next) => {
        if (active) {
          setDraftState((current) => reconcileDraftState(current, next));
          setLoading(false);
        }
      })
      .catch(() => {
        if (active) {
          setLoading(false);
        }
      });

    const id = window.setInterval(() => {
      refresh().catch(() => undefined);
    }, 3000);

    return () => {
      active = false;
      window.clearInterval(id);
    };
  }, [refresh]);

  const openDraft = useCallback(() => {
    setDraftState((current) => {
      const draftConfig = current.isDirty ? current.draftConfig : cloneConfig(current.savedBaseline);

      // Run source-mode validation when opening draft
      const validation = validateSourceMode(draftConfig);

      // Initialize field validations based on validation results
      const updatedFields = { ...current.fields };
      for (const [fieldName, fieldValidation] of Object.entries(validation.fieldValidations)) {
        updatedFields[fieldName as RuntimeDraftFieldKey] = {
          invalid: !fieldValidation.valid,
          pending: false,
          message: fieldValidation.message,
        };
      }

      return {
        ...current,
        isOpen: true,
        draftConfig,
        fields: updatedFields,
      };
    });
  }, []);

  const closeDraft = useCallback(() => {
    setDraftState((current) => ({
      ...current,
      isOpen: false,
    }));
  }, []);

  const resetDraft = useCallback(() => {
    setDraftState((current) => {
      const resetConfig = cloneConfig(current.savedBaseline);

      // Run source-mode validation when resetting
      const validation = validateSourceMode(resetConfig);

      // Initialize field validations based on validation results
      const updatedFields = createRuntimeDraftFieldState();
      for (const [fieldName, fieldValidation] of Object.entries(validation.fieldValidations)) {
        updatedFields[fieldName as RuntimeDraftFieldKey] = {
          invalid: !fieldValidation.valid,
          pending: false,
          message: fieldValidation.message,
        };
      }

      return {
        ...current,
        draftConfig: resetConfig,
        isDirty: false,
        fields: updatedFields,
      };
    });
  }, []);

  const updateDraft = useCallback((patch: Partial<RuntimeConfig>) => {
    setDraftState((current) => {
      const nextDraft = {
        ...current.draftConfig,
        ...patch,
      };

      return {
        ...current,
        isOpen: true,
        isDirty: !areConfigsEqual(nextDraft, current.savedBaseline),
        draftConfig: nextDraft,
      };
    });
  }, []);

  const updateDraftField = useCallback(<K extends RuntimeDraftFieldKey>(field: K, value: RuntimeConfig[K]) => {
    setDraftState((current) => {
      const nextDraft = {
        ...current.draftConfig,
        [field]: value,
      };

      // Run source-mode validation
      const validation = validateSourceMode(nextDraft);

      // Update field validations based on validation results
      const updatedFields = { ...current.fields };
      for (const [fieldName, fieldValidation] of Object.entries(validation.fieldValidations)) {
        updatedFields[fieldName as RuntimeDraftFieldKey] = {
          invalid: !fieldValidation.valid,
          pending: false,
          message: fieldValidation.message,
        };
      }

      return {
        ...current,
        isOpen: true,
        isDirty: !areConfigsEqual(nextDraft, current.savedBaseline),
        draftConfig: nextDraft,
        fields: updatedFields,
      };
    });
  }, []);

  const updateDraftFieldMeta = useCallback(
    (field: RuntimeDraftFieldKey, patch: Partial<RuntimeDraftFieldMeta>) => {
      setDraftState((current) => ({
        ...current,
        fields: {
          ...current.fields,
          [field]: {
            ...current.fields[field],
            invalid: false,
            pending: false,
            message: null,
            ...patch,
          },
        },
      }));
    },
    [],
  );

  // Phase 4: Model scanning for validation
  const scanModels = useCallback(async (dirPath: string | null) => {
    const resolvedDir = dirPath ?? "";

    // Set scanning state first
    setDraftState((current) => ({
      ...current,
      isScanning: true,
    }));

    try {
      const models = await scanRuntimeModels(resolvedDir);

      // Now update with results
      setDraftState((current) => {
        const modelPathInvalid = current.draftConfig.model_path
          ? !models.some((m) => m.path === current.draftConfig.model_path)
          : false;
        const modelPathMessage = current.draftConfig.model_path
          ? models.some((m) => m.path === current.draftConfig.model_path)
            ? null
            : "Model file not found in current models directory"
          : null;

        return {
          ...current,
          scannedModels: models,
          isScanning: false,
          // Validate model_path against scanned models
          fields: {
            ...current.fields,
            model_path: {
              invalid: modelPathInvalid,
              pending: false,
              message: modelPathMessage,
            },
          },
        };
      });
    } catch (error) {
      setDraftState((current) => ({
        ...current,
        scannedModels: [],
        isScanning: false,
        fields: {
          ...current.fields,
          models_dir: {
            invalid: true,
            pending: false,
            message: error instanceof Error ? error.message : String(error),
          },
        },
      }));
    }
  }, []);

  // Auto-scan models when the configured directory changes
  useEffect(() => {
    const modelsDir = draftState.liveSnapshot.config.models_dir;
    if (modelsDir) {
      scanModels(modelsDir).catch(() => undefined);
    }
  }, [draftState.liveSnapshot.config.models_dir, scanModels]);

  const commitSavedSnapshot = useCallback((next: RuntimeSnapshot, keepOpen: boolean) => {
    setDraftState((current) => ({
      ...current,
      liveSnapshot: next,
      savedBaseline: cloneConfig(next.config),
      draftConfig: cloneConfig(next.config),
      isDirty: false,
      isOpen: keepOpen,
      fields: createRuntimeDraftFieldState(),
    }));
  }, []);

  const saveDraft = useCallback(async () => {
    const blockedSnapshot = blockWhileLifecycleBusy(draftState.liveSnapshot, "save");
    if (blockedSnapshot) {
      setDraftState((current) => ({ ...current, liveSnapshot: blockedSnapshot }));
      return blockedSnapshot;
    }

    setBusy(true);
    setDraftState((current) => ({
      ...current,
      liveSnapshot: startLifecycleSnapshot(current.liveSnapshot, "save", current.liveSnapshot.status),
    }));
    try {
      const next = await saveRuntimeConfig(draftState.draftConfig);
      const resolvedNext = finalizeLifecycleSnapshot("save", "Save completed.", next);
      commitSavedSnapshot(resolvedNext, true);
      return resolvedNext;
    } finally {
      setBusy(false);
    }
  }, [commitSavedSnapshot, draftState.draftConfig]);

  const saveConfig = useCallback(async (patch: Partial<RuntimeConfig>) => {
    const blockedSnapshot = blockWhileLifecycleBusy(draftState.liveSnapshot, "save");
    if (blockedSnapshot) {
      setDraftState((current) => ({ ...current, liveSnapshot: blockedSnapshot }));
      return blockedSnapshot;
    }

    setBusy(true);
    setDraftState((current) => ({
      ...current,
      liveSnapshot: startLifecycleSnapshot(current.liveSnapshot, "save", current.liveSnapshot.status),
    }));
    try {
      const next = await saveRuntimeConfig({ ...draftState.draftConfig, ...patch });
      const resolvedNext = finalizeLifecycleSnapshot("save", "Save completed.", next);
      commitSavedSnapshot(resolvedNext, draftState.isOpen);
      return resolvedNext;
    } finally {
      setBusy(false);
    }
  }, [commitSavedSnapshot, draftState.draftConfig, draftState.isOpen]);

  const startLocal = useCallback(async () => {
    const blockedSnapshot = blockWhileLifecycleBusy(draftState.liveSnapshot, "start");
    if (blockedSnapshot) {
      setDraftState((current) => ({ ...current, liveSnapshot: blockedSnapshot }));
      return blockedSnapshot;
    }

    setBusy(true);
    setDraftState((current) => ({
      ...current,
      liveSnapshot: startLifecycleSnapshot(current.liveSnapshot, "start", "starting"),
    }));
    try {
      const next = await startRuntime();
      const resolvedNext = finalizeLifecycleSnapshot("start", "Local API started.", next);
      setDraftState((current) => reconcileDraftState(current, resolvedNext));
      return resolvedNext;
    } finally {
      setBusy(false);
    }
  }, [draftState.liveSnapshot]);

  const stopLocal = useCallback(async () => {
    const blockedSnapshot = blockWhileLifecycleBusy(draftState.liveSnapshot, "stop");
    if (blockedSnapshot) {
      setDraftState((current) => ({ ...current, liveSnapshot: blockedSnapshot }));
      return blockedSnapshot;
    }

    setBusy(true);
    setDraftState((current) => ({
      ...current,
      liveSnapshot: startLifecycleSnapshot(current.liveSnapshot, "stop", "stopping"),
    }));
    try {
      const next = await stopRuntime();
      const resolvedNext = finalizeLifecycleSnapshot("stop", "Local API stopped.", next);
      setDraftState((current) => reconcileDraftState(current, resolvedNext));
      return resolvedNext;
    } finally {
      setBusy(false);
    }
  }, [draftState.liveSnapshot]);

  const connection = useMemo(() => getRuntimeConnection(draftState.liveSnapshot), [draftState.liveSnapshot]);
  const activeLifecycleCommand = draftState.liveSnapshot.active_command;
  const lastLifecycleResult: RuntimeLifecycleResult = draftState.liveSnapshot.last_command_result;
  const lifecycleBusy = activeLifecycleCommand !== "idle";
  const applyImpact: RuntimeApplyImpact = useMemo(
    () =>
      getRuntimeApplyImpact({
        savedBaseline: draftState.savedBaseline,
        draftConfig: draftState.draftConfig,
        processRunning: draftState.liveSnapshot.process_running,
      }),
    [draftState.draftConfig, draftState.liveSnapshot.process_running, draftState.savedBaseline],
  );

  // Phase 3: Unified workspace contract
  const workspaceSummary: RuntimeWorkspaceSummary = useMemo(
    () => getRuntimeWorkspaceSummary(draftState.liveSnapshot),
    [draftState.liveSnapshot],
  );
  const workspaceHealth: RuntimeWorkspaceHealth = useMemo(
    () => getRuntimeHealthSummary(draftState.liveSnapshot),
    [draftState.liveSnapshot],
  );

  return {
    snapshot: draftState.liveSnapshot,
    liveSnapshot: draftState.liveSnapshot,
    savedBaseline: draftState.savedBaseline,
    draftConfig: draftState.draftConfig,
    draftDirty: draftState.isDirty,
    draftOpen: draftState.isOpen,
    draftFields: draftState.fields,
    connection,
    loading,
    busy,
    activeLifecycleCommand,
    lastLifecycleResult,
    lifecycleBusy,
    applyImpact,
    // Phase 3: Unified workspace contract
    workspaceSummary,
    workspaceHealth,
    refresh,
    openDraft,
    closeDraft,
    resetDraft,
    updateDraft,
    updateDraftField,
    updateDraftFieldMeta,
    saveDraft,
    saveConfig,
    startLocal,
    stopLocal,
    // Phase 4: Model scanning for validation
    scannedModels: draftState.scannedModels,
    isScanningModels: draftState.isScanning,
    scanModels,
  };
}