# 1. Goal
Check the temperature log of a refrigerated shipment. A logistics program calls the
check before it releases the shipment. The check must give one reason code for each
log that is not correct.

# 2. Open questions
None.

# 3. Context
- The exception class {{P}}CX_COLD_CHAIN exists in package $TMP. It is active.
- The class inherits from CX_STATIC_CHECK. It has the read-only attribute MV_RULE
  (type STRING), the constructor with the importing parameter IV_RULE (type STRING),
  and the redefined method GET_TEXT.
- GET_TEXT returns the text Cold chain check failed: <rule code>.
- A temperature log is a table of readings. One reading has the time offset in
  minutes (OFFSET_MIN) and the temperature in tenths of a degree Celsius
  (TEMP_TENTHS). Example: the value -185 means -18.5 degrees Celsius.

# 4. Contract
- Create the class {{P}}COLD_CHAIN_CHECK in package $TMP.
- The class is public, final, and has a public constructor.
- The class has these public types:
  - TY_READING: a structure with the fields OFFSET_MIN (type I) and TEMP_TENTHS
    (type I).
  - TT_READINGS: a standard table of TY_READING with an empty key.
  - TY_CONFIG: a structure with the fields MIN_TENTHS (type I), MAX_TENTHS
    (type I), MIN_DURATION (type I), and MAX_GAP (type I).
- The constructor has the importing parameter IS_CONFIG of type TY_CONFIG.
- The class has the method CHECK with the importing parameter IT_READINGS of type
  TT_READINGS, the returning parameter RV_MEAN of type I, and the addition
  RAISING {{P}}CX_COLD_CHAIN.
- Do not add other public methods.
- Do not change {{P}}CX_COLD_CHAIN.

# 5. Business rules
Apply the rules in this sequence. Raise the exception {{P}}CX_COLD_CHAIN with the
rule code of the first rule that fails. Pass the rule code in the parameter IV_RULE.
The rule codes are the character strings TOO_FEW, NO_START, TIME_ORDER, TOO_SHORT,
GAP, TOO_HIGH, and TOO_LOW.
The caller always passes a configuration with MIN_TENTHS less than or equal to
MAX_TENTHS.
1. If IT_READINGS has less than 2 entries, use TOO_FEW.
2. If the offset of the first entry is not 0, use NO_START.
3. If the offsets are not strictly increasing, use TIME_ORDER.
4. If the offset of the last entry is less than MIN_DURATION, use TOO_SHORT.
5. If the difference between the offsets of two consecutive entries is greater than
   MAX_GAP, use GAP.
6. Read the entries in the table order. If TEMP_TENTHS is greater than MAX_TENTHS,
   use TOO_HIGH. If TEMP_TENTHS is less than MIN_TENTHS, use TOO_LOW.
7. Else return the sum of all TEMP_TENTHS divided by the number of entries. Truncate
   the result toward zero.

# 6. Constraints
- Release target: 8.16.
- Coding standards: Clean ABAP. Method length below 40 statements. No global
  variables. No comment that restates the code.
- Out of scope: do not change {{P}}CX_COLD_CHAIN.

# 7. Acceptance
- The class is active and has no syntax error.
- The hidden tests pass.
- Write your own ABAP Unit tests for the class.