import type { CaseState } from "./caseModel";

export const PUMP_ROD_MISMATCH_M = 15;

export type EngineeringIssue = {
  severity: "warning" | "error";
  code: string;
  message: string;
};

export type EngineeringChecks = {
  issues: EngineeringIssue[];
  hasBlockingError: boolean;
};

export function runEngineeringChecks(state: CaseState): EngineeringChecks {
  const issues: EngineeringIssue[] = [];

  const activeTaper = state.taper.filter((t) => Number.isFinite(t.length) && t.length > 0);
  const rodTotal = activeTaper.reduce((acc, t) => acc + t.length, 0);
  const pumpDepth = state.pumpDepth;
  if (rodTotal > 0 && pumpDepth > 0) {
    const diff = Math.abs(pumpDepth - rodTotal);
    if (diff > PUMP_ROD_MISMATCH_M) {
      issues.push({
        severity: "error",
        code: "PUMP_ROD_MISMATCH_15M",
        message: `Pump depth (${pumpDepth.toFixed(1)}) and total rod length (${rodTotal.toFixed(
          1
        )}) differ by ${diff.toFixed(1)} m (> ${PUMP_ROD_MISMATCH_M} m limit).`
      });
    }
  }

  if (state.survey.length < 2) {
    issues.push({
      severity: "error",
      code: "SURVEY_TOO_SHORT",
      message: "Trajectory needs at least 2 survey stations."
    });
  } else {
    let nonMonotonic = false;
    for (let i = 1; i < state.survey.length; i += 1) {
      if (state.survey[i].md <= state.survey[i - 1].md) nonMonotonic = true;
    }
    if (nonMonotonic) {
      issues.push({
        severity: "error",
        code: "SURVEY_MD_NON_MONOTONIC",
        message: "Measured depth must strictly increase between survey stations."
      });
    }
    const maxMd = state.survey[state.survey.length - 1].md;
    if (pumpDepth > 0 && maxMd > 0 && maxMd < pumpDepth - 10) {
      issues.push({
        severity: "warning",
        code: "SURVEY_BELOW_PUMP_MISSING",
        message: `Trajectory ends at MD ${maxMd.toFixed(
          1
        )}, shallower than pump depth ${pumpDepth.toFixed(1)}.`
      });
    }
  }

  return {
    issues,
    hasBlockingError: issues.some((issue) => issue.severity === "error")
  };
}