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48/// Given a list of reports, selects the best tier in a tierwise fashion.
49/// The "best" criteria can be configured by `logic_` and `mode_`.
50/// Logic can be "every" or "any", which means that the reports for a given
51/// tier must either all or any be less than or equal to the reference
52/// `blockNumber_`.
53/// Mode can be "min", "max", "first" which selects between all the block
54/// numbers for a given tier that meet the lte criteria.
55/// @param reports_ The list of reports to select over.
56/// @param blockNumber_ The block number that tier blocks must be lte.
57/// @param logic_ `LOGIC_EVERY` or `LOGIC_ANY`.
58/// @param mode_ `MODE_MIN`, `MODE_MAX` or `MODE_FIRST`.
59function selectLte(
60    uint256[] memory reports_,
61    uint256 blockNumber_,
62    uint256 logic_,
63    uint256 mode_
64) internal pure returns (uint256) {
65    unchecked {
66        uint256 ret_;
67        uint256 block_;
68        bool anyLte_;
69        uint256 length_ = reports_.length;
70        for (uint256 tier_ = 1; tier_ <= 8; tier_++) {
71            uint256 accumulator_;
72            // Nothing lte the reference block for this tier yet.
73            anyLte_ = false;
74
75            // Initialize the accumulator for this tier.
76            if (mode_ == MODE_MIN) {
77                accumulator_ = TierConstants.NEVER_REPORT;
78            } else {
79                accumulator_ = 0;
80            }
81
82            // Filter all the blocks at the current tier from all the
83            // reports against the reference tier and each other.
84            for (uint256 i_ = 0; i_ < length_; i_++) {
85                block_ = TierReport.tierBlock(reports_[i_], tier_);
86
87                if (block_ <= blockNumber_) {
88                    // Min and max need to compare current value against
89                    // the accumulator.
90                    if (mode_ == MODE_MIN) {
91                        accumulator_ = block_.min(accumulator_);
92                    } else if (mode_ == MODE_MAX) {
93                        accumulator_ = block_.max(accumulator_);
94                    } else if (mode_ == MODE_FIRST && !anyLte_) {
95                        accumulator_ = block_;
96                    }
97                    anyLte_ = true;
98                } else if (logic_ == LOGIC_EVERY) {
99                    // Can short circuit for an "every" check.
100                    accumulator_ = TierConstants.NEVER_REPORT;
101                    break;
102                }
103            }
104            if (!anyLte_) {
105                accumulator_ = TierConstants.NEVER_REPORT;
106            }
107            ret_ = TierReport.updateBlockAtTier(
108                ret_,
109                tier_ - 1,
110                accumulator_
111            );
112        }
113        return ret_;
114    }
115}